Drop local copies of ION headers

All projects now fetch this reliably from the actual kernel source tree

Change-Id: Ib044239bcea6e84759e05d75f718583dbf6e0839

Conflicts:
	include/linux/msm_ion.h
Revert "enable sf optimizations for virtual displays"

This reverts commit 7f61a21f0b983318d986cae661d702a81b2ac2b0.