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
15 files changed