keyguard: fix chopped layout on hdpi msim devices

* adapted from commit fa06992ab7e49fe1e056787dd281384d92290be1

Change-Id: I23ebb212c96e3ef8aecebb43760cbea7d441b1fd
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_frameworks_base into android-4.4_new