msm: Update the assign api to secure buffers

The assign call apis have been updated by TZ to
include more usecases. Update the secure_buffer
api files with the same. The system secure heap
needs to be updated to reflect the change in
the api calls.

Change-Id: Idc784ddac222e6ad9f5defafc422e6e3fb88aa0c
Signed-off-by: Neeti Desai <neetid@codeaurora.org>