screenshooter: remove useless cast

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
diff --git a/src/screenshooter.c b/src/screenshooter.c
index c98e2f9..4e32db5 100644
--- a/src/screenshooter.c
+++ b/src/screenshooter.c
@@ -558,8 +558,7 @@
 static void
 recorder_binding(struct weston_seat *seat, uint32_t time, uint32_t key, void *data)
 {
-	struct weston_seat *ws = (struct weston_seat *) seat;
-	struct weston_compositor *ec = ws->compositor;
+	struct weston_compositor *ec = seat->compositor;
 	struct weston_output *output;
 	struct wl_listener *listener = NULL;
 	struct weston_recorder *recorder;