audio: msm8660: Use msm_ion header

 * The ion.h header has long since removed MSM-specific bits.
 * Even ancient kernels should have support for at least a dummy
   msm_ion.h, so enable it for compatibility with new kernels.

Change-Id: Ie3381913c8ff8a8e61038d8962f1455131dc4659
Merge branch 'cm' into HEAD