Synchronize access to sim data

Mutiple refactors have attempted to remove work from the main
thread. However, KeyguardUpdateMonitor assumes main thread
access to protect data structures like simData. Add synchronized
blocks around mSimData to prevent concurrent modifications.

Fixes: 371663342
Test: manual - race condition crash
Flag: EXEMPT bugfix
Change-Id: I32479d8900dd9719929d0604ca403e5c2095a030