libweston: remove unused backend_init() arguments

Backends do not have access to command line elements nor weston_config
anymore. They use the backend-specific config APIs now.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>
diff --git a/src/compositor-rdp.c b/src/compositor-rdp.c
index 4fc7c74..49d9f10 100644
--- a/src/compositor-rdp.c
+++ b/src/compositor-rdp.c
@@ -1290,8 +1290,7 @@
 }
 
 WL_EXPORT int
-backend_init(struct weston_compositor *compositor, int *argc, char *argv[],
-	     struct weston_config *wconfig,
+backend_init(struct weston_compositor *compositor,
 	     struct weston_backend_config *config_base)
 {
 	struct rdp_backend *b;