msm: secure_buffer: use explicitly-sized types for TZ communication

Some types currently in use for passing data to TZ (like `unsigned
long') have different sizes under different build configurations (32 bit
vs 64 bit, etc). TZ dictates the sizes of the structures that are passed
back-and-forth and they cannot change. Use explicitly-sized types for
any such structures.

Change-Id: Ib6a671f137a875fbabcb045f595cefcbe3616beb
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>