Define guard() usage for PCM stream locking and use it in appropriate
places.

The pair of snd_pcm_stream_lock() and snd_pcm_stream_unlock() can be
presented with guard(pcm_stream_lock) now.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240227085306.9764-23-tiwai@suse.de