wayland: Don't scale XWayland pointer cursor sprites

We don't have any way of knowing what the intended size of a XWayland
cursor is supposed to be, so lets do what we do with regular XWayland
surfaces and don't scale them. The result is that cursor sprites of
HiDPI aware X11 clients will show correctly, but non-aware clients may
have tiny cursor sprites.

https://bugzilla.gnome.org/show_bug.cgi?id=755099