Staging: android: binder: More offset validation.

Make sure offsets don't point to overlapping flat_binder_object
structs.

Change-Id: I425ab0c46fbe2b00ed679c5becf9e8140395eb40
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Git-commit: 457c3cd05958b8397211ae1f6dd3c3d325f4c0ea
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: Neeti Desai <neetid@codeaurora.org>
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>