remove duplicate security settings in lockscreen prefs

this removes duplicate code, the duplicate security options from
lockscreen prefs (these already exist in security), and CM's
isCmSecurity boolean which isn't applicable to vanir.

This reverts commit 396a1c774eab017348ab824c5a59c45e2ccf7cbe.

Change-Id: Ie2e528e19c0d44be3d8eb9b5a7a208e6e5bdce05