ALSA: hda - add device list & select info of display pins to codec proc file

If a display codec supports multi-stream transport on the pins, the pin's
device list length and device entries will be exposed to codec proc file.

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