drm/amdgpu: enable gfxoff quirk on HP 705G4

[ Upstream commit 2c7795e2 ]

Enabling gfxoff quirk results in perfectly usable
graphical user interface on HP 705G4 DM with R5 2400G.

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

Signed-off-by: Peng Liu <liupeng01@kylinos.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>