Suppress Registration Errors when WFC disabled

There is still the possibility of IMS registration
failing for a time after the user has disabled WFC.
This causes registration error messages
to keep popping up. This change suppresses
those notifications when the WFC setting is off.

Bug: 64412124
Test: Manual
Merged-In: I77d5a15644c3735ca99ef58d6b92f8092807c5fe
Merged-In: I5c0b4531655bed57e5a8efe0ebffe13a027e597f
Change-Id: I5c0b4531655bed57e5a8efe0ebffe13a027e597f