Changes

vlr: refactor the reject cause codes

Use reject cause consistent within the VLR.
Convert the GMM cause code to reject cause, which contains the
exact same values. Reject cause includes both CS and PS cause codes,
because CS and PS cause codes uses the same numbering space.
See 24.008 annex G.

Filter early the HLR provided cause code based on the CN domain,
some values are invalid and will be converted into network failure.

Change-Id: Ib269e9f865cd23f9f2c0a1bac0e17c95974c1c9f