Add density bucket for hdpi and xhdpi

follow these commits from cm
https://github.com/CyanogenMod/android_vendor_cm/commit/8526bd18078e58d7391f1b09299a2c3fef3b481b
https://github.com/CyanogenMod/android_vendor_cm/commit/4da88ceb96a2be054d5c4f68516eae08f21fea77