selftests: mptcp: add mptcp_lib_verify_listener_events

To avoid duplicated code in different MPTCP selftests, we can add and use
helpers defined in mptcp_lib.sh.

The helper verify_listener_events() is defined both in mptcp_join.sh and
userspace_pm.sh, export it into mptcp_lib.sh and rename it with mptcp_lib_
prefix. Use this new helper in both scripts.

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-v1-13-4f42c347b653@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -835,26 +835,11 @@ test_prio()
 
 verify_listener_events()
 {
-	local evt=$1
-	local e_type=$2
-	local e_family=$3
-	local e_saddr=$4
-	local e_sport=$5
-	local type
-	local family
-	local saddr
-	local sport
-
-	type=$(mptcp_lib_evts_get_info type $evt $e_type)
-	family=$(mptcp_lib_evts_get_info family $evt $e_type)
-	sport=$(mptcp_lib_evts_get_info sport $evt $e_type)
-	if [ $family ] && [ $family = $AF_INET6 ]; then
-		saddr=$(mptcp_lib_evts_get_info saddr6 $evt $e_type)
+	if mptcp_lib_verify_listener_events "${@}"; then
+		test_pass
 	else
-		saddr=$(mptcp_lib_evts_get_info saddr4 $evt $e_type)
+		test_fail
 	fi
-
-	check_expected "type" "family" "saddr" "sport"
 }
 
 test_listener()