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/iucs.c b/src/libmsc/iucs.c
index f9ed759..1e4ab19 100644
--- a/src/libmsc/iucs.c
+++ b/src/libmsc/iucs.c
@@ -172,7 +172,7 @@
 		uint8_t pdisc = gh->proto_discr & 0x0f;
 		OSMO_ASSERT(pdisc != GSM48_PDISC_RR);
 
-		msc_dtap(conn, msg);
+		ran_conn_dtap(conn, msg);
 	} else {
 		/* allocate a new connection */
 
@@ -189,7 +189,7 @@
 			abort();
 
 		/* ownership of conn hereby goes to the MSC: */
-		msc_compl_l3(conn, msg, 0);
+		ran_conn_compl_l3(conn, msg, 0);
 	}
 
 	return 0;