udev-seat: Make udev_input own its own udev object reference

No functional changes; API simplification in preparation for multiple
input backends.

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
diff --git a/src/compositor-fbdev.c b/src/compositor-fbdev.c
index d1013e8..f8d2fe0 100644
--- a/src/compositor-fbdev.c
+++ b/src/compositor-fbdev.c
@@ -824,7 +824,7 @@
 
 		weston_compositor_damage_all(&compositor->base);
 
-		udev_input_enable(&compositor->input, compositor->udev);
+		udev_input_enable(&compositor->input);
 	} else {
 		weston_log("leaving VT\n");
 		udev_input_disable(&compositor->input);