mm: ashmem: Add cache clean and invalidate ioctls for ashmem

Change-Id: I9475feb06c961cb8b27b434eaf3b54d2666331d4
Orig-Change-Id: Idc120f9f869c1a68e5f012327aa7f599ac065fce
CRs-fixed: 291124
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>
mm: ashmem: Make sure vma is valid while flushing

Ensure that the vma that the ashmem region is tied to
is valid before flushing and hold the mm semaphore so
that the vma does not get destroyed from under while
it's being flushed.

Change-Id: I5216aa3a4fa983f97909c1132d12abe777f60530
CRs-Fixed: 326685
Orig-Change-Id: I86320ffe9e6570e6ffa7dda68ab26be7aed86afd
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>