mach-msm: Use ION_CP_MM_HEAP_ID instead of ION_CAMERA_HEAP_ID

Hi Arne,
some msm7x30 devices, like semc and huawei devices mantained by Michael Bestas (mikeNG) and Rudolf Tammekivi (Blefish), can't have a fully working media stuff (camera + video playback/recording) when using ION_CAMERA_HEAP_ID and GRALLOC_USAGE_PRIVATE_ADSP_HEAP on rom side.
If you have some time, please, give a try with this commit to switch from ION_CAMERA_HEAP_ID to ION_CP_MM_HEAP_ID.
On rom side, the following commit must be applied on media-caf side:
http://review.cyanogenmod.org/#/c/62863/

If everything is ok, please, make also a code review to that patch.

I think it's better to have the best compatibility between every msm7x30 device that has been ION ported (with PMEM ADSP only).

Thanks a lot.
Have a nice Sunday.
Best regards.