cosmetic: gsm_data.h, README: rename CSCN to MSC

We're discarding the name OsmoCSCN for the benefit of OsmoMSC. But "CSCN" has
already crept into the master branch in two places; apply the rename.

See OS#1958

Change-Id: Ib4274eb3c172ada1fe7f05746740b456370bc93d
diff --git a/openbsc/README b/openbsc/README
index 88ea328..d01b2cf 100644
--- a/openbsc/README
+++ b/openbsc/README
@@ -9,7 +9,7 @@
  * OsmoBSC - a pure GSM BSC, speaking Abis/IP to the BTS and A/IP to the MSC
  * OsmoBSC-MGCP - MGCP helper to the OsmoBSC software
  * OsmoNITB - a BSC+MSC+VLR+HLR+SMSC "Network in the box".
- * OsmoCSCN - a voice CN with A/IP and IuCS/IP towards the BSC and/or HNB-GW
+ * OsmoMSC - a voice CN with A/IP and IuCS/IP towards the BSC and/or HNB-GW
  * OsmoSGSN - a GPRS SGSN with Gb/IP and IuPS/IP towards the PCU and/or HNB-GW
  * Osmo-GbProxy - a Proxy to aggregate many Gb links as one Gb link to the SGSN
  * OsmoBSCNAT - a gateway aggregating many A links as one A link to the MSC