commit de5d0ad5 upstream.

This is essentially a partial revert of the commit [b1920c21:
'ALSA: hda - Enable runtime PM on Panther Point'].  There was a bug
report showing the HD-audio bus hang during runtime PM on HP Spectre
XT.
Reported-by: Dang Sananikone <dang.sananikone@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>