tcp: restore formatting of macros for tcp_skb_cb sacked field

Commit b82d1bb4 inadvertendly placed unrelated new code between
TCPCB_EVER_RETRANS and TCPCB_RETRANS and the other macros that refer
to the sacked field in the struct tcp_skb_cb (probably because there
was a misleading empty line there). This commit fixes up the
formatting so that all macros related to the sacked field are adjacent
again.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>