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.

psyke83: adjust for 2.6.35 kernel

Orig-Change-Id: Iac039678e1c3f15d87e67aa667f7e9883ca16669
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>

Change-Id: I9cb6a958ab75efa089538f3e9795ebce75500a85