ALSA: hda - Record the current power state before suspend/resume calls

Currently we deal with single codec and suspend codec callbacks for
all S3, S4 and runtime PM handling.  But it turned out that we want
distinguish the call patterns sometimes, e.g. for applying some init
sequence only at probing and restoring from hibernate.

This patch slightly modifies the common PM callbacks for HD-audio
codec and stores the currently processed PM event in power_state of
the codec's device.power field, which is currently unused.  The codec
callback can take a look at this event value and judges which purpose
it's being called.

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