Revert "tcp: fix conflicting types for tcp_write_xmit"

This reverts commit 102470011938498a30b24ca06c3f73b7ae05cd89.
Revert "tcp: early retransmit"

This reverts commit 3381da2658d0a50c29303162dcf90d4fca83050a.
Revert "tcp: tcp small queues"

This reverts commit a29300d3425a3c2185e6f7367194bd625e2be049.