keyguard: fix chopped layout on hdpi msim devices

* adapted from commit fa06992ab7e49fe1e056787dd281384d92290be1

Change-Id: I23ebb212c96e3ef8aecebb43760cbea7d441b1fd
(cherry picked from commit 8808d97f3f31e6bfac4047022260a0e8da78714d)