gpu: ion: Add dummy msm_ion header file

The msm specific parts of ion.h are being moved into a new header
file. For now, add a dummy header file to get clients transitioned
over.

Change-Id: Iac039678e1c3f15d87e67aa667f7e9883ca16669
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Add heap_mask to ion_allocation_data
legacy_ion.h: a backwards-compatibility copy of ion.h

cloned from include/linux/ion.h at:

commit b6b0b65325e6f5eb5fcfd88d270f710d947f7962
Author: Brian Muramatsu <btmura@google.com>
Date:   Mon Jul 30 22:54:08 2012 -0700

    Add heap_mask to ion_allocation_data

Signed-off-by: Iliyan Malchev <malchev@google.com>
msm_ion.h: switch to using legacy_ion.h

Signed-off-by: Iliyan Malchev <malchev@google.com>
gpu: ion: Add compatibility with future changes

Several changes are pending to be pulled in which are
not compatible with our changes. Specifically, a new
field to the allocation ioctl is added and the ioctl
numbers for cache flushing need to be changed.
Add these changes now until full changes can be pulled
in the future.

Change-Id: I9540495e25c7b6c414a6e3719f66f2cd9f78c585
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>