net/xia: replace sk_no_check to sk_no_check_{rx,tx}

This patch just complies with commit
28448b80456feafe07e2d05b6363b00f61f6171e:
net: Split sk_no_check into sk_no_check_{rx,tx}
xia/serval: drop parameter of sk->sk_data_ready()

This patch just complies with commit
676d23690fb62b5d51ba5d659935e9f7d9da9f8e:
net: Fix use after free by removing length arg from
sk_data_ready callbacks.
xia/serval: replace ctl_table to struct ctl_table

This patch just complies with commit
e5eea0981a3840f3f39f43d2d00461c4c24018e7:
sysctl: remove typedef ctl_table
xia/serval: drop parameter of sk_rcvqueues_full()

This patch just complies with commit
274f482d33a309c87096f2983601ceda2761094e:
sock: remove skb argument from sk_rcvqueues_full
xia/serval: drop constant TCP_CONG_RTT_STAMP

Commit 740b0f1841f6e39085b711d41db9ffb07198682b
(tcp: switch rtt estimations to usec resolution)
has removed this contant, and it turned out Serval doesn't need it
because Serval only implements Reno congestion control algorithm.
xia/serval: drop min_cwnd member of tcp_congestion_ops

This patch just complies with commit
45f7435968363816f8fc4c6abef692808534140d:
tcp: remove unused min_cwnd member of tcp_congestion_ops
net/xia: update signature of dst.output methods

This patch just complies with commit
aad88724c9d54acb1a9737cb6069d8470fa85f74:
ipv4: add a sock pointer to dst->output() path.
xia/u4id: replace local_df to ignore_df

This patch just complies with commit
60ff746739bf805a912484643c720b6124826140:
net: rename local_df to ignore_df.
xia/u4id: pass tunnel sock to ip_queue_xmit()

This patch complies with commits
  - b0270e91014dabfceaf37f5b40ad51bbf21a1302:
    ipv4: add a sock pointer to ip_queue_xmit(), and
  - 31c70d5956fc3d1abf83e9ab5e1d8237dea59498:
    l2tp: keep original skb ownership.

This patch also takes advantage of the change to ip_queue_xmit()
to avoid sock_hold() and sock_put() the tunnel sock.