selftests: mptcp: connect: add dedicated port counter

This patch adds a new dedicated counter 'port' instead of TEST_COUNT
to increase port numbers in mptcp_connect.sh.

This can avoid outputting discontinuous test counters.
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/20240308-upstream-net-next-20240308-selftests-mptcp-unification-v1-2-4f42c347b653@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -33,6 +33,7 @@ do_tcp=0
 checksum=false
 filesize=0
 connect_per_transfer=1
+port=$((10000 - 1))
 
 if [ $tc_loss -eq 100 ];then
 	tc_loss=1%
@@ -313,8 +314,7 @@ do_transfer()
 	local local_addr="$6"
 	local extra_args="$7"
 
-	local port
-	port=$((10000+TEST_COUNT))
+	port=$((port + 1))
 	TEST_COUNT=$((TEST_COUNT+1))
 
 	if [ "$rcvbuf" -gt 0 ]; then
@@ -710,7 +710,7 @@ EOF
 
 	echo "INFO: test $msg"
 
-	TEST_COUNT=10000
+	port=$((20000 - 1))
 	local extra_args="-o TRANSPARENT"
 	do_transfer ${listener_ns} ${connector_ns} MPTCP MPTCP \
 		    ${connect_addr} ${local_addr} "${extra_args}"