drm/radeon: do not continue after error from r600_ib_test

This return statement got dropped while fixing the conflicts introduced
in 7a7e8734ac.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/evergreen.c

@@ -3191,6 +3191,7 @@ static int evergreen_startup(struct radeon_device *rdev)
 	if (r) {
 		DRM_ERROR("radeon: failed testing IB (%d).\n", r);
 		rdev->accel_working = false;
+		return r;
 	}
 
 	r = r600_audio_init(rdev);