ANDROID: staging: ion: optimize cache operation for non-cached buffer

The non-cached ion buffer is flushed when allocated.
And then, that is is always mapped as non-cached after allocation.
In the absence of caching, cache maintenance operations
become unnecessary. However dma_buf_ops tries to maintain
cache coherency for non-cached buffer on begin[end]_cpu_access
and map[unmap]_dma_buf functions.

It creates unnecessary overhead, so let's remove it.

Bug: 151775080

Signed-off-by: Hyesoo Yu <hyesoo.yu@samsung.com>
Change-Id: I168117c7002aec7930c84168d15816a09750b7d8
Signed-off-by: Hridya Valsaraju <hridya@google.com>
(cherry picked from commit 2c3b4cba8ab38d7eb9f474c78f9b4c70867bf71d)
Signed-off-by: Hridya Valsaraju <hridya@google.com>