Revert "xfrm: store and rely on direction to construct offload flags"

This reverts commit 7f6afb1b which is
commit 482db2f1 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Iba6b908e1e5fb6bf43c462360135521cff88ad40
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>