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

This reverts commit 76ff31c0 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: I1acd257f2c006da26224e2dc610d0242ff1d344c
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>