Remove VcnStatusCallback#onEnteredSafemode().

This CL removes VcnStatusCallback#onEnteredSafeMode(). This method was
previously used to notify callbacks when their VCN entered Safe Mode.
However, this is not needed now that
VcnStatusCallback#onVcnStatusChanged(int) is defined.

Bug: 1597023
Test: atest FrameworksVcnTests
Change-Id: I8e47de9bf6763cd38025a552bee710673dddf843
3 files changed