mptcp: drop duplicate header inclusions

The headers net/tcp.h, net/genetlink.h and uapi/linux/mptcp.h are included
in protocol.h already, no need to include them again directly. This patch
removes these duplicate header inclusions.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240305-upstream-net-next-20240304-mptcp-misc-cleanup-v1-1-c436ba5e569b@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>