Reset cell broadcast config before enabling all channels

Before cell broadcast config service enabling all channels, it
reset all channels that were previously enabled. This will make
sure the full channel config can be pushed down to modem. This
also solved the issue that channel config not sending to modem
when SIM is swapped. Note that a hidden API is added and will
be unhide in the next Android release.

Fix: 155027085
Test: Manual
Merged-In: Id571b990f4e45aea5bbab0dbadce48dda7b2bc56
Change-Id: Id571b990f4e45aea5bbab0dbadce48dda7b2bc56