ALSA: usb-audio: Support read-only clock selector control

Clock selector control might be read-only. Add corresponding checks
to prevent sending control requests that would fail.

Signed-off-by: Alexander Tsoy <alexander@tsoy.me>
Link: https://lore.kernel.org/r/20240125205457.28258-1-alexander@tsoy.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>