Add Acer Aspire Ethos 8951G model quirk

This notebook has 6 built in speakers for 5.1 surround support, however
only two got autodetected and have also not been assigned correctly.

This patch enables all speakers and also fixes muting when headphones are
plugged in.

The speaker layout is as follows:

pin 0x15 Front Left / Front Right
pin 0x18 Front Center / Subwoofer
pin 0x1b Rear Left / Rear Right (Surround)

The quirk will be enabled automatically on this hardware, but can also be
activated manually via the model=aspire-ethos module parameter.

Caveat: pin 0x1b is shared between headphones jack and surround speakers.
When headphones are plugged in, the surround speakers get muted
automatically by the hardware, however all other speakers remain
unmuted. Currently it's not possible to make use of the generic automute
function in the driver, because such shared pins are not supported.

If we would change the pin settings to identify the pin as headphones,
the surround channel and thus the ability to select 5.1 profiles would
get lost.

This quirk solves the above problem by monitoring jack state of 0x1b and
by connecting/disconnecting all remaining speaker pins when something
gets plugged in or unplugged from the headphones jack port.

Signed-off-by: Sergey Bostandzhyan <jin@mediatomb.cc>
Link: https://lore.kernel.org/r/20190906093343.GA7640@xn--80adja5bqm.su
Signed-off-by: Takashi Iwai <tiwai@suse.de>