ALSA: als4000: Fix capture trigger chip->mode race

ALSA: als4000: Fix capture trigger chip->mode race

snd_als4000_capture_trigger() updates chip->mode under mixer_lock,
while snd_als4000_set_rate() and snd_als4000_playback_trigger()
serialize the same rate-lock state with reg_lock.

The PCM core serializes callbacks only per acted-on substream, or for an
explicitly linked group, so unlinked playback and capture streams can
run concurrently.

That leaves two races on ALS4000 rate-lock state:
- playback and capture trigger callbacks can concurrently update
  chip->mode and lose one of the SB_RATE_LOCK bits
- snd_als4000_set_rate() can observe chip->mode without the capture
  lock bit set and reprogram the shared sample rate while capture is
  being started

Fix this by taking reg_lock as the outer lock in
snd_als4000_capture_trigger() and nesting mixer_lock only for the CR1E
write. This keeps chip->mode serialized with the rest of the ALS4000
rate-lock users while preserving the existing CR1E programming
sequence.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260417-als4000-capture-trigger-race-v1-1-daeffc2feb67@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>