compositor: Don't pass output to notify_keyboard_focus

Doesn't make sense and was only used to distinguish between enter/leave.
diff --git a/src/compositor.c b/src/compositor.c
index 5c5331e..1bdca11 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -1675,8 +1675,7 @@
 
 WL_EXPORT void
 notify_keyboard_focus(struct wl_input_device *device,
-		      uint32_t time, struct weston_output *output,
-		      struct wl_array *keys)
+		      uint32_t time, struct wl_array *keys)
 {
 	struct weston_input_device *wd =
 		(struct weston_input_device *) device;
@@ -1684,7 +1683,7 @@
 	struct wl_surface *surface;
 	uint32_t *k;
 
-	if (output) {
+	if (keys) {
 		wl_array_copy(&wd->input_device.keys, keys);
 		wd->modifier_state = 0;
 		wl_array_for_each(k, &device->keys) {