Revert "blue-common: disable some unimplemented overlays"

Things are back!

This reverts commit 6032c0df8111ce1474bf56242eded1824b7d9b0f.
blue-common: use legacy_mmap to fix Adreno errors

W/Adreno-GSL( 3072): <ioctl_kgsl_device_getproperty:651>: mmap failed: errno 22 Invalid argument

And no more flickering.

Change-Id: Ib592eb16780975f6bbcf21dd6b7861580baa66db