In the former commits, the callback of isochronous context runs on usual
work process. In the case, ALSA PCM device has a flag, nonatomic, to
acquire mutex lock instead of spin lock for PCM substream group.

This commit uses the flag. It has an advantage in the case that ALSA PCM
application uses the large size of intermediate buffer, since it takes
too long time even in tasklet softIRQ to process many of isochronous
packets, then result in the delay of system event due to disabled IRQ so
long. It is avertible to switch to nonatomic operation.
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Tested-by: Edmund Raile <edmund.raile@protonmail.com>
Link: https://lore.kernel.org/r/20240904125155.461886-6-o-takashi@sakamocchi.jpSigned-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>