ALSA: hda/hdmi - enable automatic runtime pm for AMD HDMI codecs by default

So that we can power down the GPU and audio to save power.

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20191122214353.582899-5-alexander.deucher@amd.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_hdmi.c

@@ -4063,6 +4063,7 @@ static int atihdmi_init(struct hda_codec *codec)
 					    ATI_VERB_SET_MULTICHANNEL_MODE,
 					    ATI_MULTICHANNEL_MODE_SINGLE);
 	}
+	codec->auto_runtime_pm = 1;
 
 	return 0;
 }