bsc_api: Do not use RLL inside the SMS code, handle SAPI n REJECT

Directly send a SMS using the send method, in case of an error
we will need to find the transaction and free the SMS and the
transaction.
diff --git a/openbsc/src/osmo_msc.c b/openbsc/src/osmo_msc.c
index 97f6e6f..b5bb371 100644
--- a/openbsc/src/osmo_msc.c
+++ b/openbsc/src/osmo_msc.c
@@ -25,8 +25,14 @@
 #include <openbsc/bsc_api.h>
 #include <openbsc/debug.h>
 
+#include <openbsc/gsm_04_11.h>
+
 static void msc_sapi_n_reject(struct gsm_subscriber_connection* conn, int dlci)
 {
+	int sapi = dlci & 0x7;
+
+	if (sapi == UM_SAPI_SMS)
+		gsm411_sapi_n_reject(conn);
 }
 
 static struct bsc_api msc_handler = {