drm/amdgpu: Enable gfxoff quirk on MacBook Pro

drm/amdgpu: Enable gfxoff quirk on MacBook Pro

BugLink: https://bugs.launchpad.net/bugs/1969857
commit 4593c1b6d159f1e5c35c07a7f125e79e5a864302 upstream.

Enabling gfxoff quirk results in perfectly usable graphical user
interface on MacBook Pro (15-inch, 2019) with Radeon Pro Vega 20 4 GB.

Without the quirk, X server is completely unusable as every few seconds
there is gpu reset due to ring gfx timeout.

Signed-off-by: Tomasz Moń <desowin@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>