wayland: Fix wayland display handle request message
See #2583
Some time ago wayland rework landed (pull !2479 (merged), commit 8c3e33d4) that changed display handle request message from GstWaylandDisplayHandleContextType
to GstWlDisplayHandleContextType
.
But not all places used gst/wayland/wayland.h header, in subprojects/gst-plugins-base/gst-libs/gst/gl/gstglutils.c string is hardcoded (probably to break good -> bad header dependency).