PIN Lockscreen: Fix mdpi layout issues

Before: http://i.imgur.com/qmsy8Sr.png
After: http://i.imgur.com/rzHtwu4.png

Change-Id: Id718fde086ec5a9cebe75307d3668a54a38a37c5
Signed-off-by: kyryljan-serhij <kirilyan.sergei@gmail.com>
Signed-off-by: Michael Bestas <mikeioannina@gmail.com>