egl: drop left-over function prototype

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Marcin Ĺšlusarz <marcin.slusarz@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6037>
1 file changed