[ALSA] hda-intel - Don't do suspend if already powered down

In the power-saving mode, the suspend is done dynamically at power-down.
So we don't have to call suspend stuff explicitly if it's already
powered down.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>