MNCC: pass the actual 'struct msgb' down the mncc_recv() callback

this is required as we no longer have a dequeue-handler that can take
care of free()ing the message after passing it to the MNCC handler.
diff --git a/openbsc/src/bsc_init.c b/openbsc/src/bsc_init.c
index 01ff70a..86a1c8d 100644
--- a/openbsc/src/bsc_init.c
+++ b/openbsc/src/bsc_init.c
@@ -1184,7 +1184,7 @@
 	return 0;
 }
 
-int bsc_bootstrap_network(int (*mncc_recv)(struct gsm_network *, int, void *),
+int bsc_bootstrap_network(int (*mncc_recv)(struct gsm_network *, struct msgb *),
 			  const char *config_file)
 {
 	struct telnet_connection dummy_conn;