For a start, src/share/examples/wpa_supplicant/wpa_supplicand.conf now has an example for a WPA network with no SSID broadcast.

For kicks, here's the full dmesg output:

Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 7.99.21 (RPI2) #14: Thu Nov 26 01:36:58 CET 2015
	feyrer@promise.local:/Users/feyrer/work/NetBSD/cvs/src-current/obj.evbarm-Darwin-XXX/sys/arch/evbarm/compile/RPI2
total memory = 944 MB
avail memory = 925 MB
sysctl_createv: sysctl_create(machine_arch) returned 17
timecounter: Timecounters tick every 10.000 msec
mainbus0 (root)
cpu0 at mainbus0 core 0: 600 MHz Cortex-A7 r0p5 (Cortex V7A core)
cpu0: DC enabled IC enabled WB disabled EABT branch prediction enabled
cpu0: 32KB/32B 2-way L1 VIPT Instruction cache
cpu0: 32KB/64B 4-way write-back-locking-C L1 PIPT Data cache
cpu0: 512KB/64B 8-way write-through L2 PIPT Unified cache
vfp0 at cpu0: NEON MPE (VFP 3.0+), rounding, NaN propagation, denormals
cpu1 at mainbus0 core 1
cpu2 at mainbus0 core 2
cpu3 at mainbus0 core 3
obio0 at mainbus0
bcmicu0 at obio0: Multiprocessor
armgtmr0 at obio0: ARMv7 Generic 64-bit Timer (19200 kHz)
armgtmr0: interrupting on irq 3
timecounter: Timecounter "armgtmr0" frequency 19200000 Hz quality 500
bcmmbox0 at obio0 intr 193: VC mailbox
vcmbox0 at bcmmbox0
vchiq0 at obio0 intr 194: BCM2835 VCHIQ
bcmpm0 at obio0: Power management, Reset and Watchdog controller
bcmdmac0 at obio0: DMA0 DMA2 DMA4 DMA5 DMA8 DMA9 DMA10
bcmrng0 at obio0: RNG
plcom0 at obio0 intr 185
plcom0: txfifo disabled
plcom0: console
genfb0 at obio0
genfb0: framebuffer at 0x3d876000, size 1280x720, depth 32, stride 5120
wsdisplay0 at genfb0 kbdmux 1
wsmux1: connecting to wsdisplay0
wsdisplay0: screen 0-3 added (default, vt100 emulation)
sdhc0 at obio0 intr 190: SDHC controller
sdhc0: interrupting on intr 190
dwctwo0 at obio0 intr 137: USB controller
bcmspi0 at obio0 intr 182: SPI
spi0 at bcmspi0: SPI bus
bsciic0 at obio0 intr 181: BSC0
iic0 at bsciic0: I2C bus
bsciic1 at obio0 intr 181: BSC1
iic1 at bsciic1: I2C bus
bcmgpio0 at obio0: GPIO [0...31]
gpio0 at bcmgpio0: 32 pins
bcmgpio1 at obio0: GPIO [32...53]
gpio1 at bcmgpio1: 22 pins
bcmcm at obio0 not configured
bcmpwm at obio0 not configured
usb0 at dwctwo0: USB revision 2.0
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
cpu3: 600 MHz Cortex-A7 r0p5 (Cortex V7A core)
cpu3: DC enabled IC enabled WB disabled EABT branch prediction enabled
cpu3: 32KB/32B 2-way L1 VIPT Instruction cache
cpu3: 32KB/64B 4-way write-back-locking-C L1 PIPT Data cache
cpu3: 512KB/64B 8-way write-through L2 PIPT Unified cache
vfp3 at cpu3: NEON MPE (VFP 3.0+), rounding, NaN propagation, denormals
cpu2: 600 MHz Cortex-A7 r0p5 (Cortex V7A core)
cpu2: DC enabled IC enabled WB disabled EABT branch prediction enabled
cpu2: 32KB/32B 2-way L1 VIPT Instruction cache
cpu2: 32KB/64B 4-way write-back-locking-C L1 PIPT Data cache
cpu2: 512KB/64B 8-way write-through L2 PIPT Unified cache
vfp2 at cpu2: NEON MPE (VFP 3.0+), rounding, NaN propagation, denormals
cpu1: 600 MHz Cortex-A7 r0p5 (Cortex V7A core)
cpu1: DC enabled IC enabled WB disabled EABT branch prediction enabled
cpu1: 32KB/32B 2-way L1 VIPT Instruction cache
cpu1: 32KB/64B 4-way write-back-locking-C L1 PIPT Data cache
cpu1: 512KB/64B 8-way write-through L2 PIPT Unified cache
vfp1 at cpu1: NEON MPE (VFP 3.0+), rounding, NaN propagation, denormals
sdhc0: SDHC 3.0, rev 153, platform DMA, 250000 kHz, HS SDR50 3.3V, re-tuning mode 1, 1024 byte blocks
sdmmc0 at sdhc0 slot 0
uhub0 at usb0: vendor 0000 DWC2 root hub, class 9/0, rev 2.00/1.00, addr 1
uhub0: 1 port with 1 removable, self powered
IPsec: Initialized Security Association Processing.
ld0 at sdmmc0: <0x03:0x5344:SU16G:0x80:0x000dd697:0x0f1>
ld0: 15193 MB, 7717 cyl, 64 head, 63 sec, 512 bytes/sect x 31116288 sectors
ld0: 4-bit width, SDR50, 100.000 MHz
uhub1 at uhub0 port 1: vendor 0424 product 9514, class 9/0, rev 2.00/2.00, addr 2
uhub1: multiple transaction translators
uhub1: 5 ports with 4 removable, self powered
usmsc0 at uhub1 port 1
usmsc0: vendor 0424 product ec00, rev 2.00/2.00, addr 3
usmsc0: Ethernet address b8:27:eb:b9:ca:25
ukphy0 at usmsc0 phy 1: OUI 0x00800f, model 0x000c, rev. 3
ukphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
run0 at uhub1 port 2
run0: Ralink 802.11 n WLAN, rev 2.00/1.01, addr 4
run0: MAC/BBP RT5390 (rev 0x0502), RF RT5370 (MIMO 1T1R), address 7c:dd:90:3f:54:00
run0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
run0: 11g rates: 1Mbps 2Mbps 5.5Mbps 11Mbps 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
boot device: ld0
root on ld0a dumps on ld0b
root file system type: ffs
kern.module.path=/stand/evbarm/7.99.21/modules
vchiq: local ver 6 (min 3), remote ver 6.
vcaudio0 at vchiq0: auds
WARNING: no TOD clock present
WARNING: using filesystem time
WARNING: CHECK AND RESET THE DATE!
audio0 at vcaudio0: half duplex, playback, capture, independent
wsdisplay0: screen 4 added (default, vt100 emulation)