Telephony: Fix NullPointerException in CdmaSmsAddress parsing

When CdmaSmsAddress parse fails to encode in 4 bit, it tries for 8 bit,
however earlier calls to filterNumericSugar() could have nullified the
address that is being parsed.  Fix to check for null, and use original
address to continue parsing.
CRs-Fixed: 389695

Change-Id: Ic0f8973148972d56e6699dda73ddac4e6f8e6b97