[ALSA] hda-codec - Add missing input controls for Cxt5047 test model

The input volume/switch elements are missing in Cxt5047 test model.
Also the patch includes some code clean ups.

Signed-off-by: Marc Boucher <marc@linuxant.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>