The recent addition of automatic mic-muting is broken in some cases.
The code assumes that the pin nids <= 0x18, but the digital pins can
be less than 0x18.
Also, it assumes the front-mic being the internal mic, but it depends
on the hardware implementation actually.

Instead of complex case-fixes, better to disable the code as now.
Signed-off-by: Takashi Iwai <tiwai@suse.de>