ALSA: hda - Move some definitions to new hda_priv.h

Later commits adding support for hda platform drivers will want to use
the same defines and structures. Put them in a place reachable by both
hda_intel and the new platform driver.

This is a mostly a direct copy with a few whitespace and comment
changes to make checkpatch happy.

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