rename some RAN conn related stuff to ran_conn_*

Following previous rename of gsm_subscriber_connection:

Some functions and #defines are still called like "msc_conn" or just "msc_",
while they are clearly about a RAN conn.

To avoid confusion with the future separate concepts of MSC roles and a RAN
connection, rename all those to match the common "ran_conn" prefix.

Change-Id: Ia17a0a35f11911e00e19cafb5d7828d729a69640
diff --git a/src/libmsc/silent_call.c b/src/libmsc/silent_call.c
index 6c6e217..c6c31a0 100644
--- a/src/libmsc/silent_call.c
+++ b/src/libmsc/silent_call.c
@@ -57,7 +57,7 @@
 			conn->lchan->ts->nr, conn->lchan->ts->trx->arfcn);
 #endif
 		conn->silent_call = 1;
-		ran_conn_get(conn, MSC_CONN_USE_SILENT_CALL);
+		ran_conn_get(conn, RAN_CONN_USE_SILENT_CALL);
 		/* increment lchan reference count */
 		osmo_signal_dispatch(SS_SCALL, S_SCALL_SUCCESS, &sigdata);
 		break;
@@ -162,7 +162,7 @@
 #endif
 
 	conn->silent_call = 0;
-	ran_conn_put(conn, MSC_CONN_USE_SILENT_CALL);
+	ran_conn_put(conn, RAN_CONN_USE_SILENT_CALL);
 
 	return 0;
 }