LockScreen: Option to hide initial page hints (2/2)

This will add an option to hide the initial page hints
that are shown left and right when the device is turned on.

Change-Id: I188bcc0b52715a56ee8b6d2fc7cc6908592cea0c
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>