Switch to KeyguardManager.isDeviceSecure.

isKeyguardSecure also returns true when SIM PIN is required. We don't
care about that because entering SIM PIN does not unlock keys
requiring user authentication. isDeviceSecure returns true only if
secure lock screen is set up, which is exactly what we want.

Bug: 18088752
Change-Id: I47b21f3351f55c11e8e9bcfd7654762973dd9271
1 file changed