staging: android: binder: Add deref_helper() macro

This patch adds a deref_helper() macro that will be used to dereference
the binder offsets on 64bit systems where the offset is either a 32bit
or a 64bit value, depending on the userpace used (32bit /64bit)

This patch is a temporary patch that will be extended with 32bit compat
handling.

Change-Id: Ic8fac7ce1e73055ba02f215861dc235be3c20f5a
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
Git-commit: b91f0620b69ecb8b753a5053944178b5da624638
Git-repo: git://linux-arm.org/linux-2.6-armdroid.git


Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>