drm/amdgpu/mmhub2: set clock gating for navi12

add navi12 define
Signed-off-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/mmhub_v2_0.c

@@ -407,6 +407,7 @@ int mmhub_v2_0_set_clockgating(struct amdgpu_device *adev,
 	switch (adev->asic_type) {
 	case CHIP_NAVI10:
 	case CHIP_NAVI14:
+	case CHIP_NAVI12:
 		mmhub_v2_0_update_medium_grain_clock_gating(adev,
 				state == AMD_CG_STATE_GATE ? true : false);
 		mmhub_v2_0_update_medium_grain_light_sleep(adev,