This patch added a new member named csum_enabled in struct mptcp_sock,
used a dummy mptcp_is_checksum_enabled() helper to initialize it.
Also added a new member named mptcpi_csum_enabled in struct mptcp_info
to expose the csum_enabled flag.
Acked-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Geliang Tang <geliangtang@gmail.com> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>