ALSA: hda - Fix unbalanced runtime PM refcount after S3/S4

When a machine goes to S3/S4 after power-save is enabled, the runtime
PM refcount might be incorrectly decreased because the power-down
triggered soon after resume assumes that the controller was already
powered up, and issues the pm_notify down.

This patch fixes the incorrect pm_notify call simply by checking the
current value properly.

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>