drm/radeon/dpm: require rlc for dpm

The rlc is required for dpm to work properly, so if
the rlc ucode is missing, don't enable dpm.  Enabling
dpm without the rlc enabled can result in hangs.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_pm.c

@@ -1176,7 +1176,10 @@ int radeon_pm_init(struct radeon_device *rdev)
 	case CHIP_VERDE:
 	case CHIP_OLAND:
 	case CHIP_HAINAN:
-		if (radeon_dpm == 1)
+		/* DPM requires the RLC */
+		if (!rdev->rlc_fw)
+			rdev->pm.pm_method = PM_METHOD_PROFILE;
+		else if (radeon_dpm == 1)
 			rdev->pm.pm_method = PM_METHOD_DPM;
 		else
 			rdev->pm.pm_method = PM_METHOD_PROFILE;