MAINTAINERS: add Neal to TCP maintainers

Neal Cardwell has been indispensable in TCP reviews
and investigations, especially protocol-related.
Neal is also the author of packetdrill.

Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

MAINTAINERS

@@ -16525,6 +16525,7 @@ F:	tools/testing/selftests/net/mptcp/
 
 NETWORKING [TCP]
 M:	Eric Dumazet <[email protected]>
+M:	Neal Cardwell <[email protected]>
 L:	[email protected]
 S:	Maintained
 F:	Documentation/networking/net_cachelines/tcp_sock.rst