ALSA: hda - Add hdaudio bus modalias support

This patch just adds modalias sysfs entry to each hdaudio bus entry.

[rewritten to call the common helper function by tiwai]

Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Reviewed-by: Vinod Koul <vinod.koul@intel.com>
Tested-by: Subhransu S Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>