drm/amdgpu/cz: store the forced dpm level

So the selected forced level shows up properly in sysfs.

Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1717,6 +1717,8 @@ static int cz_dpm_force_dpm_level(struct amdgpu_device *adev,
 		break;
 	}
 
+	adev->pm.dpm.forced_level = level;
+
 	return ret;
 }