LockPatternUtils: isSecure: respect profile settings

When the lock screen is set to secure and overridden to insecure
by profile settings, isSecure() would return true causing confusion
to some code.

For example, attempting to use a lockscreen shortcut
to launch an activity will cause the device to soft-reboot due to
recursive calling and a stack overflow.

Change-Id: I02984671c2a047765f4da1f6a44bb19dea5bf2d3