ion: msm: move msm extensions to staging

The Ion driver has moved to staging. Move the msm-specific extensions as
well. Also Update some of the build infrastructure to correctly export
the UAPI files from the staging directory.

Change-Id: I75a6760e0e2f0c9ae37196b0573fa151a8d7a33c
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>