drm/radeon/kms/pm: don't enable pm if there is only on power state

Just adds overhead when the power state will never change.
Signed-off-by: NAlex Deucher <alexdeucher@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_pm.c

@@ -113,7 +113,7 @@ int radeon_pm_init(struct radeon_device *rdev)
 
 	INIT_DELAYED_WORK(&rdev->pm.idle_work, radeon_pm_idle_work_handler);
 
-	if (radeon_dynpm != -1 && radeon_dynpm) {
+	if ((radeon_dynpm != -1 && radeon_dynpm) && (rdev->pm.num_power_states > 1)) {
 		rdev->pm.state = PM_STATE_PAUSED;
 		DRM_INFO("radeon: dynamic power management enabled\n");
 	}