ALSA: usb-audio: Do not expose sticky mixers

ALSA: usb-audio: Do not expose sticky mixers

Some devices' mixers are sticky, which accept SET_CUR but do absolutely
nothing. Registering these mixers confuses userspace and results in
ineffective volume control.

Check if a mixer is sticky by setting the volume to the maximum or
minimum value and checking for effectiveness afterward. Prevent the
mixer from being registered if it turns out to be sticky.

Quirky device sample:

  usb 7-1: New USB device found, idVendor=0e0b, idProduct=fa01, bcdDevice= 1.00
  usb 7-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  usb 7-1: Product: Feaulle Rainbow
  usb 7-1: Manufacturer: Generic
  usb 7-1: SerialNumber: 20210726905926
  (Mic Capture Volume)

Signed-off-by: Rong Zhang <i@rong.moe>
Link: https://patch.msgid.link/20260411-uac-sticky-mixer-v1-3-29d62717befd@rong.moe
Signed-off-by: Takashi Iwai <tiwai@suse.de>