KeyGuard: Fix the wrong Plmn/SPN display.

Currently in KeyGuardUpdateMonitor, while handling the intent
SPN_STRING_UPDATED_ACTION, spn and plmn gets updated even before
MSG_SUBINFO_RECORD_UPDATED is handled. This results in wrong
updation of SPN and PLMN values.

Fix is to ensure plmn and spn are updated with right values got
from SPN_STRING_UPDATED_ACTION intent. This is done by copying
the original plmn and spn got from intent to the already updated
plmn and spn by MSG_SUBINFO_RECORD_UPDATED.

Change-Id: I34cfef19d437cb91fcaeae16b9c12bf08311f056
CRs-Fixed: 816911