Fix SetupWizard black screen issue for EDU devices

This fixes a problem where EDU devices show a black screen if
the device is rebooted after setting a pin/pattern/password but
before completing SetupWizard.

The issue is that the system doesn't expect to see a state
where the device is not provisioned but has a pin/pattern/password
because it wasn't possible before. With the addition of the ability
for EDU devices to add a pin/pattern/password, we can now get
into this unforseen state.

The fix ignores provisioning if a password is set so that the
user can reach the security screen to unlock the device and
continue with SetupWizard.

Fixes bug 18022051

Change-Id: Ie88a75530d964c02458c25866f0629877214edf4