Allow access to deprecated LOCK_PATTERN_ENABLED flag.

It is possible that older platforms may have not cleared the lock pattern,
but instead only checked this flag to determine the lock pattern enabled
state. In such cases, upgrading to a platform with that only checks the
lock pattern can lead to the lock screen being re-enabled by accident.
These new methods allow this condition to be identified and resolved.

Bug: 26029690
Change-Id: I8f7ebc0e1915049afe49c219c87010aa38a16244