data-device: Remove redundant and confusing assignment

We were assigning drag from the resource user data, which was wrong
(resource data is the weston_seat) and confusing since drag is later
assigned newly malloc()ed memory.

src/data-device.c

@@ -353,7 +353,7 @@ data_device_start_drag(struct wl_client *client, struct wl_resource *resource,
 		       struct wl_resource *icon_resource, uint32_t serial)
 {
 	struct weston_seat *seat = wl_resource_get_user_data(resource);
-	struct weston_drag *drag = wl_resource_get_user_data(resource);
+	struct weston_drag *drag;
 	struct weston_surface *icon = NULL;
 
 	if (seat->pointer->button_count == 0 ||