Changes

vlr: extend the subscriber invalidate callback with reasons

The VLR must be allowed to notify the MSC if a subscriber becomes invalid.
There are multiple cases when this happens:
a) if the subscriber didn't do a Location Update Procedure within the
given periodic timer.
b) if the HLR does a Cancel Location Procedure with reason withdraw
c) if the HLR does a Cancel Location Procedure with reason update location.

Only in case c) must the user be informed with the cause code sent by the HLR.

Change-Id: Ie5b687318b106a230fcee52deba86649641004b3