mptcp: remove the redundant assignment of 'new_ctx->tcp_sock' in subflow_ulp_clone()

The variable has already been assigned in the subflow_create_ctx(),
So we don't need to reassign this variable in the subflow_ulp_clone().

Signed-off-by: MoYuanhao <moyuanhao3676@163.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241106071035.2591-1-moyuanhao3676@163.com


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