remove unused VTY command "location updating reject cause"

OsmoMSC is using whatever reject cause is apropriate in the given
situation.  This user-configurable reject cause only had relevance
in OsmoNITB, and hence it is an unused parameter that can be removed
in OsmoMSC.

Related: OS#2528
Change-Id: Ie1f39e706477aaf42051877b52d4b3ae1c5f138e
6 files changed