42fdcd9fd917 broke my snd_uaudio(4)

hello,

since the commit:

42fdcd9fd917 snd_uaudio(4): Fix config detection with defaults set.

my snd_uaudio(4) no longer works.  the symptom is that applications
attempting to play audio hang forever, and no audio is produced.
reverting this commit fixed the problem.

the issue only occurs if i have this set in /boot/loader.conf:

hw.usb.uaudio.default_bits=32
hw.usb.uaudio.default_rate=48000

removing these two settings makes audio work correctly again.

my audio device:

ugen3.2: <Focusrite Scarlett 18i20 USB> at usbus3
uaudio0 on uhub1
uaudio0: <Focusrite Scarlett 18i20 USB, class 239/2, rev 2.00/6.6c, addr 1> on usbus3
uaudio0: Play[0]: 48000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 192000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 176400 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 96000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 88200 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 48000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Play[0]: 44100 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 48000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 192000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 176400 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 96000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 88200 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 48000 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: Record[0]: 44100 Hz, 20 ch, 32-bit S-LE PCM format, 2x4ms buffer.
uaudio0: MIDI sequencer.
pcm0 on uaudio0
uaudio0: No HID volume keys found.

and /dev/sndstat:

FreeBSD Audio Driver (64bit 2009061500/amd64)
Installed devices:
pcm0: <Focusrite Scarlett 18i20 USB> on uaudio0 (1p:0v/1r:0v) default
	snddev flags=0x3e6<AUTOVCHAN,SOFTPCMVOL,BUSY,MPSAFE,REGISTERED,BITPERFECT,VPC>
	[pcm0:play:dsp0.p0]: spd 48000, fmt 0x01401000, flags 0x2000110c, 0x00000001, pid 22326 (virtual_oss)
	interrupts 115908, underruns 0, feed 115907, ready 123440 [b:30720/15360/2|bs:131040/65520/2]
	channel flags=0x2000110c<RUNNING,TRIGGERED,BUSY,HAS_SIZE,BITPERFECT>
	{userland} -> feeder_root(0x01401000) -> {hardware}
	[pcm0:record:dsp0.r0]: spd 48000, fmt 0x01401000, flags 0x2000112c, 0x00000001, pid 22326 (virtual_oss)
	interrupts 115930, overruns 97, feed 229796, hfree 30720, sfree 65440 [b:30720/15360/2|bs:65440/32720/2]
	channel flags=0x2000112c<RUNNING,TRIGGERED,SLEEPING,BUSY,HAS_SIZE,BITPERFECT>
	{hardware} -> feeder_root(0x01401000) -> {userland}
Installed devices from userspace:
dsp.full: <Virtual OSS> (play/rec)
dsp.record: <Virtual OSS> (play/rec)
dsp: <Virtual OSS> (play/rec)

	regards, lexi.