Some HP laptops have a mute mute LED controlled by a pin VREF.  The
Realtek codec driver updates the VREF via vmaster hook by calling
snd_hda_set_pin_ctl_cache().

This works fine as long as the driver is running in a normal mode.
However, when the VREF change happens during the codec being in
runtime PM suspend, the regmap access will skip and postpone the
actual register change.  This ends up with the unchanged LED status
until the next runtime PM resume even if you change the Master mute
switch.  (Interestingly, the machine keeps the LED status even after
the codec goes into D3 -- but it's another story.)

For improving this usability, let the driver temporarily powering up /
down only during the pin VREF change.  This can be achieved easily by
wrapping the call with snd_hda_power_up_pm() / *_down_pm().

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199073
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>