Don't store lockout deadline in lockSettings

The deadline is enforced in gatekeeper, which persists after reboot.
Users should not see the lockout timer after rebooting the device if it
was previously in lockout, until an unlock attempt occurs.

Fixes: 66443036

Test: 1) fail pattern five times
2) reboot device
3) go to bouncer, lockout timer should not show
4) upon entering pattern, timeout should show (if done fast enough)

Change-Id: Ie07945b40c2f482fd1df7102ba96283ae9d98d75