Add a column named is_locked in carriers table, defaule value is 0. Property "ro.config.lock_apn" controls if this feature needed or not. If feature needed , set is_locked to 1 when load prebuilt APNs. Issue:GRANITEFLY-744 Change-Id: If16818f3693f31462d9de4ad1dabd7a9eb91d363 Signed-off-by: Firefly <service@t-firefly.com>