drm/dp_mst: Drop DRM_ERROR() on kzalloc() fail in drm_dp_mst_handle_up_req()

Checkpatch was complaining about this - there's no need for us to print
errors when kzalloc() fails, as kzalloc() will already WARN for us. So,
let's fix that before converting things to make checkpatch happy.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210326203807.105754-20-lyude@redhat.com

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -4109,10 +4109,9 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
 		return 0;
 
 	up_req = kzalloc(sizeof(*up_req), GFP_KERNEL);
-	if (!up_req) {
-		DRM_ERROR("Not enough memory to process MST up req\n");
+	if (!up_req)
 		return -ENOMEM;
-	}
+
 	INIT_LIST_HEAD(&up_req->next);
 
 	drm_dp_sideband_parse_req(&mgr->up_req_recv, &up_req->msg);