ALSA: hda: Intel: enable automatic runtime pm for HDMI codecs by default

Enable runtime PM of the HDMI audio codec on the latest Intel platforms.
So the HD-A controller or HDMI codec can suspend when idle timeout by
default and release the GFX power well.
The patch influences HSW/BDW/BYT/BSW/SKL. Eariler platforms and third
party analog codecs will not be influenced.

Signed-off-by: Lu, Han <han.lu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>