ALSA: hda/realtek: Add quirk for mute LEDs on HP ENVY x360 15-eu0xxx

The LED for the mic mute button is controlled by GPIO2.
The mute button LED is slightly more complex, it's controlled by two bits
in coeff 0x0b.

Signed-off-by: Fabian Vogt <fabian@ritter-vogt.de>
Link: https://lore.kernel.org/r/2693091.mvXUDI8C0e@fabians-envy
Signed-off-by: Takashi Iwai <tiwai@suse.de>