msm: smd: add support for non-default shared memory areas

Add support via platform data to access shared data in shared memory
regions outside of the default shared memory region.  Provide bounds
checking when instructed to use a non-default shared memory region.

Change-Id: I48e6b272c7a2c51644b363a0e2212bbedcaa8c14
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>