ALSA: hda - Add support for ALC5505 DSP power-save mode

This patch adds the power-saving control for ALC5505 DSP on some
Realtek codecs.

Signed-off-by: Kailang Yang <kailang@realtek.com>
Tested-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>