Merge branch 'tcp-follow-up-for-dccp-removal'

Merge branch 'tcp-follow-up-for-dccp-removal'

Kuniyuki Iwashima says:

====================
tcp: Follow up for DCCP removal.

As I mentioned in [0], TCP still has code for DCCP.

This series cleans up such leftovers.

[0]: https://patch.msgid.link/20250410023921.11307-3-kuniyu@amazon.com

v1: https://lore.kernel.org/20250821061540.2876953-1-kuniyu@google.com
====================

Link: https://patch.msgid.link/20250822190803.540788-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>