Lockscreen: allow widgets to use more space on tablets (2/2)

aka: use that gorgeous screen

add overlay so tablets will have more space for widgets

Change-Id: Iad5f6529012583ee135a37169efc5746d1dc5db1
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
Merge "Lockscreen: allow widgets to use more space on tablets (2/2)" into jb-mr1