ipv4: ipv4: Cleanup the comments in tcp_yeah.c

This cleanup the comments in tcp_yeah.c.
1.The old link is dead,use a new one to instead.
2.'lin' add nothing useful,remove it.
3.do not use C99 // comments.

Signed-off-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>