ALSA: hda - Initialize missing bass speaker pin for ASUS AIO ET2700

Add a fixup entry for the missing bass speaker pin 0x16 on ASUS ET2700
AiO desktop.  The channel map will be added in the next patch, so that
this can be backported easily to stable kernels.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=65961


Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>