staging: android: binder: fix ABI for 64bit Android

This patch fixes the ABI for 64bit Android userspace.
BC_REQUEST_DEATH_NOTIFICATION and BC_CLEAR_DEATH_NOTIFICATION claim
to be using struct binder_ptr_cookie, but they are using a 32bit handle
and a pointer.

On 32bit systems the payload size is the same as the size of struct
binder_ptr_cookie, however for 64bit systems this will differ. This
patch adds struct binder_handle_cookie that fixes this issue for 64bit
Android.

Since there are no 64bit users of this interface that we know of this
change should not affect any existing systems.

Change-Id: I8909cbc50aad48ccf371270bad6f69ff242a8c22
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>