ALSA: hda - Move low level functions to hda_controller

Share more code from hda_intel.  This moves the link control and
initialization to hda_controller.  The code will also be used by an
hda platform driver.

Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>