ion: update documentation

Some of the documentation has gotten out of sync with the recent Ion
API changes. Update out-of-date function headers to reflect the new
API.

Change-Id: I7ce6da2b2c4464d58af7bd59066f0b4873e65bfc
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
1 file changed