HiKey/HiKey960: Fix up new dmabuf_system_heap_device sepolicy fallout

Hridya recently got some patches merged to add new default sepolicy
for the dmabuf_system_heap_device (/dev/dma_heap/system).

However, since HiKey960 already had its own policy for
/dev/dma_heap/system, this causes conflicts which break gralloc
as well as future system use of the dmabuf heaps.

So refactor the policy to avoid relabeling the system heap, or
labeling the /dev/dma_heap/ directory. Also add permissions for
gralloc to access the new dmabuf_system_heap_device, and take
care to open the dmabuf heaps as READONLY, as RW isn't necessary
and the policy limits to RO.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: I574f9231f1d04f3b36b4f75145f2e698b9009508
5 files changed