Send out a new SPN_STRINGS_UPDATED broadcast if the sub ID changes.

The sub ID is part of the broadcast's extras, so the broadcast needs to
be refreshed if it changes.
Also move the PLMN/SPN localization from Keyguard to here so that the
localized name is written to the SIM DB.

Change-Id: I7e4ee04b7b9a0ddcaebad89a3c68661accd3f1c5