libweston: Use struct timespec for motion events

Change code related to motion events to use struct timespec to represent
time.

This commit is part of a larger effort to transition the Weston codebase
to struct timespec.

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

libweston-desktop/seat.c

@@ -108,7 +108,7 @@ weston_desktop_seat_popup_grab_pointer_focus(struct weston_pointer_grab *grab)
 
 static void
 weston_desktop_seat_popup_grab_pointer_motion(struct weston_pointer_grab *grab,
-					      uint32_t time,
+					      const struct timespec *time,
 					      struct weston_pointer_motion_event *event)
 {
 	weston_pointer_send_motion(grab->pointer, time, event);