ion: msm: update custom caching ioctls for new handle format

The userspace API for Ion handles has changed slightly. Update the MSM
caching ioctls to work with the new format.

Change-Id: I6dee3190f5cad117a4d7059f1c7f0f01e05692c0
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>