[PATCH 5.15.y] selftests: mptcp: add missing kconfig for NF Filter

["Matthieu Baerts (NGI0)" <matttbe@kernel.org>]

Since the commit mentioned below, 'mptcp_join' selftests is using
IPTables to add rules to the Filter table.

It is then required to have IP_NF_FILTER KConfig.

This KConfig is usually enabled by default in many defconfig, but we
recently noticed that some CI were running our selftests without them
enabled.

Fixes: 8d014eaa9254 ("selftests: mptcp: add ADD_ADDR timeout test case")
Cc: stable@vger.kernel.org
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 3645c844902bd4e173d6704fc2a37e8746904d67)
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Notes:
 - some conflicts because new kconfig have been added later. We only
   need the added one: CONFIG_IP_NF_FILTER
---
 tools/testing/selftests/net/mptcp/config | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/net/mptcp/config b/tools/testing/selftests/net/mptcp/config
index 3f9e540fee570..15914a078e630 100644
--- a/tools/testing/selftests/net/mptcp/config
+++ b/tools/testing/selftests/net/mptcp/config
@@ -17,3 +17,4 @@ CONFIG_NETFILTER_XTABLES=m
 CONFIG_NETFILTER_XT_MATCH_BPF=m
 CONFIG_NF_TABLES_IPV4=y
 CONFIG_NF_TABLES_IPV6=y
+CONFIG_IP_NF_FILTER=m
-- 
2.43.0