drm/amdgpu: enable gfxoff quirk on HP 705G4

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 <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c

···
 	{ 0x1002, 0x69af, 0x106b, 0x019a, 0xc0 },
 	/* https://bbs.openkylin.top/t/topic/171497 */
 	{ 0x1002, 0x15d8, 0x19e5, 0x3e14, 0xc2 },
+	/* HP 705G4 DM with R5 2400G */
+	{ 0x1002, 0x15dd, 0x103c, 0x8464, 0xd6 },
 	{ 0, 0, 0, 0, 0 },
 };