By default, there is no sound on Asus UX391UA on Linux.

This patch adds sound support on Asus UX391UA. Tested working by three
different users.

The problem has also been described at
https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1784485Signed-off-by: Wandrille RONCE <w@ndrille.fr>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>