msm: ADSPRPC: Support for secure context banks

Add support for secure session that checks whether the
buffer being passed was allocated from a secure heap and
appropriately maps the buffers in the secure context bank.

Change-Id: If590f65d033e264c04f0ad782895b02765ff4f3d
Signed-off-by: Sathish Ambley <sathishambley@codeaurora.org>