[ALSA] hda-codec - Fix build without CONFIG_SND_HDA_GENERIC

Fixed the build error from patch_sigmatel.c when built without
CONFIG_SND_HDA_GENERIC by defining a dummy function to return error.
Also, clean up hda_codec.c by removing unneeded ifdefs (the compiler
will optimize out).

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>