cc: remove non-working sctp support

[tuexen]

Summary

As suggested by lstewart, remove the non-working SCTP support in the TCP congestion control modules. SCTP has a similar functionality (although not using kernel loadable modules), on which the TCP stuff even was built on, but the integration was never done.

No functional changes intended.

[tuexen]

As suggested by Peter: rename to pointer to the struct tcpcb from tcp to tp.

[cc]

Looks good to me, after the comment update for struct cc_var.

sys/netinet/cc/cc.h

89–90

This whole comment can be removed now or just can be repeated with the comment from its usage in tcpcb.

struct cc_var t_ccv; /* congestion control specific vars */

[tuexen]

Address comment from cc.

[tuexen]

sys/netinet/cc/cc.h

89–90

Comment removed.