[ALSA] soc - Ensure PCMs are suspended

This fixes a bug whereby PCMs were not being suspended when the rest of the
audio subsystem was suspended.

Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>