ALSA: hda - Make the inv dmic handling for Realtek use generic parser

From what I can see, the generic parser is now good enough to handle
Realtek's inverted dmic handling, so let's remove the special handling
and use the generic parser instead.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>