ALSA: hda/realtek: Unify LED helper code

Both mute and mic-mute LED callbacks do almost similar tasks with just
different bits.  Factor out the common code and use them from the
callbacks for simplification.

This ended up with covering the forgotten stuff, too; e.g. VREF LED
handling required the temporary power up/down that was missing for the
mute LED, or some forgotten polarity checks are added.

Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20200618110842.27238-13-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>