[ALSA] Add Conexant audio support to the HD Audio driver

This driver adds limited support for the Conexant 5045 and 5047 HD Audio
codecs.  Some issues still need to be resolved.  The code is based
primarily on code from the Analog Devices AD1981 support and the Realtek
ALC260 support.  Some code came from the original code developed by Alex
Pototskiy (see alsa bugtracker 2485).

Signed-off-by: Tobin Davis <tdavis@dsl-only.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>