drm/amdgpu: add gfxoff feature mask

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/include/amd_shared.h

@@ -125,6 +125,7 @@ enum PP_FEATURE_MASK {
 	PP_SOCCLK_DPM_MASK = 0x1000,
 	PP_DCEFCLK_DPM_MASK = 0x2000,
 	PP_OVERDRIVE_MASK = 0x4000,
+	PP_GFXOFF_MASK = 0x8000,
 	PP_ACG_MASK = 0x10000,
 };