ALSA: hda/hdmi - enable runtime pm for CI AMD display audio

We are able to power down the GPU and audio via the GPU driver
so flag these asics as supporting runtime pm.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20210105175245.963451-1-alexander.deucher@amd.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>