Revert "vxlan: Avoid unnecessary updates to FDB 'used' time"

This reverts commit 9238419f which is
commit 9722f834 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: I8c14a8b4dc692c107dbe0ece12df1c56d461a265
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>