telephony: Fix the crash issue during receiving MMS due to

           Firewall feature.

 - When receiving a MMS, it will check whether the incoming
   message's sender phone number is in the blacklist. It would
   crash if treat the MMS WAP PUSH message as a SMS message in
   the original implementation.

Change-Id: Ib63b0d0aa328b3689d8226aaa70a9200c2c4476b