wayland: Fix restarting cursor animation

wayland: Fix restarting cursor animation

When an animated cursor was set and the previous cursor animation delay
happened to be the same, we wouldn't restart the animation timeout and
just return G_SOURCE_CONTINUE assuming the timer would continue. This
assumption is however only valid if the function was called from the
timeout, which is not the case.

Instead also arm the timer also if there is no previous timer active.