drm/nouveau/kms/nv50-: fix drm-get-put.cocci warnings

Use drm_*_get() and drm_*_put() helpers instead of drm_*_reference() and
 drm_*_unreference() helpers.

Generated by: scripts/coccinelle/api/drm-get-put.cocci

Fixes: 30ed49b55b ("drm/nouveau/kms/nv50-: move code underneath dispnv50/")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -1007,7 +1007,7 @@ nv50_mstm_destroy_connector(struct drm_dp_mst_topology_mgr *mgr,
 	mstc->port = NULL;
 	drm_modeset_unlock(&drm->dev->mode_config.connection_mutex);
 
-	drm_connector_unreference(&mstc->connector);
+	drm_connector_put(&mstc->connector);
 }
 
 static void