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/a_iface.c b/src/libmsc/a_iface.c
index fa0cb5f..82519d6 100644
--- a/src/libmsc/a_iface.c
+++ b/src/libmsc/a_iface.c
@@ -629,7 +629,7 @@
 			uint32_t conn_id = conn->a.conn_id;
 			LOGPCONN(conn, LOGL_NOTICE, "Dropping orphaned RAN connection\n");
 			/* This call will/may talloc_free(conn), so we must save conn_id above */
-			msc_clear_request(conn, GSM48_CC_CAUSE_SWITCH_CONG);
+			ran_conn_clear_request(conn, GSM48_CC_CAUSE_SWITCH_CONG);
 
 			/* If there is still an SCCP connection active, remove it now */
 			if (check_connection_active(conn_id)) {