ALSA: pcm: Simplify snd_pcm_action_lock_irq()

The function snd_pcm_action_lock_irq() can be much simplified by
simply wrapping snd_pcm_action() with the stream lock.  This was
rather the original idea, but later it was open coded for
optimization.  However, looking at the optimization part closely, one
notices that the probability of the optimized path is quite low; in
normal situations, the linked stream action happens only for the
triggered substream, thus the operation becomes identical.  So the
code simplification has a clear win, especially because we have now
doubly codes for both atomic and non-atomic locks.

Signed-off-by: Takashi Iwai <tiwai@suse.de>