selftests: mptcp: sockopt: drop mptcp_connect var

Global var mptcp_connect defined at the front of mptcp_sockopt.sh is
duplicate with local var mptcp_connect defined in do_transfer(), drop
this useless global one.

Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231025-send-net-next-20231025-v1-9-db8f25f798eb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: geliangtang

tools/testing/selftests/net/mptcp/mptcp_sockopt.sh

@@ -11,7 +11,6 @@ cout=""
 ksft_skip=4
 timeout_poll=30
 timeout_test=$((timeout_poll * 2 + 1))
-mptcp_connect=""
 iptables="iptables"
 ip6tables="ip6tables"