msm: Add support to allow access to shared memory

The entire HLOS region is locked, to prevent non HLOS access,
which might cause memory scribbling. The shared memory driver
unlocks the HLOS regions assigned to the clients, by calling
into the secure environment.

Change-Id: I1904434a97dd167f3e6534853887963821da96ae
Signed-off-by: Neeti Desai <neetid@codeaurora.org>