data-device: Update drag icon position from configure and motion handlers

We can now update the drag icon position directly from the configure
handler or the grab motion handler, and no longer need
weston_seat_update_drag_surface().
diff --git a/src/compositor.h b/src/compositor.h
index 5a9349d..45054f5 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -334,8 +334,6 @@
 weston_seat_set_keyboard(struct weston_seat *seat, struct weston_keyboard *keyboard);
 void
 weston_seat_set_touch(struct weston_seat *seat, struct weston_touch *touch);
-void
-weston_seat_update_drag_surface(struct weston_seat *seat, int dx, int dy);
 
 void
 weston_pointer_init(struct weston_pointer *pointer);
@@ -474,6 +472,7 @@
 	struct weston_pointer_grab drag_grab;
 	struct weston_surface *drag_surface;
 	struct wl_listener drag_surface_destroy_listener;
+	int32_t drag_dx, drag_dy;
 
 	uint32_t num_tp;
 
@@ -856,8 +855,6 @@
 weston_compositor_offscreen(struct weston_compositor *compositor);
 void
 weston_compositor_sleep(struct weston_compositor *compositor);
-void
-weston_compositor_update_drag_surfaces(struct weston_compositor *compositor);
 struct weston_surface *
 weston_compositor_pick_surface(struct weston_compositor *compositor,
 			       wl_fixed_t x, wl_fixed_t y,