Use -mcpu=cortex-a15 for krait

Based on https://android.googlesource.com/platform/build/+/d195c6d14e027f12f63508afed245a1ce469c936

Change-Id: Ib409c915c5302cdb44d49978456b7d1cc6a2a250
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
Allow devices to specify certain ro. props via TARGET_UNIFIED_DEVICE

This modifies buildinfo.sh to not set model, name, description, and
fingerprint in build.prop. These can then be set via custom init
lib.
This also fixes ota_from_target_files to function without these
props being preset.

Change-Id: I5dc6fa19267a0e5374b07fc04db0766661da492d
Signed-off-by: Arnav Gupta <championswimmer@aokp.co>
Merge remote-tracking branch 'aokp/kitkat' into kitkat