selftests: net: add more missing kernel config

The reuseport_addr_any.sh is currently skipping DCCP tests and
pmtu.sh is skipping all the FOU/GUE related cases: add the missing
options.

Signed-off-by: Paolo Abeni <[e-mail]>
Reviewed-by: Eric Dumazet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/config

···
 CONFIG_INET_DIAG=y
 CONFIG_INET_ESP=y
 CONFIG_INET_ESP_OFFLOAD=y
+CONFIG_NET_FOU=y
+CONFIG_NET_FOU_IP_TUNNELS=y
 CONFIG_IP_GRE=m
 CONFIG_NETFILTER=y
 CONFIG_NETFILTER_ADVANCED=y
 CONFIG_NF_CONNTRACK=m
+CONFIG_IPV6_SIT=y
+CONFIG_IP_DCCP=m
 CONFIG_NF_NAT=m
 CONFIG_IP6_NF_IPTABLES=m
 CONFIG_IP_NF_IPTABLES=m
···
 CONFIG_NET_CLS_U32=m
 CONFIG_NET_IPGRE_DEMUX=m
 CONFIG_NET_IPGRE=m
+CONFIG_NET_IPIP=y
 CONFIG_NET_SCH_FQ_CODEL=m
 CONFIG_NET_SCH_HTB=m
 CONFIG_NET_SCH_FQ=m
···
 CONFIG_TRACEPOINTS=y
 CONFIG_NET_DROP_MONITOR=m
 CONFIG_NETDEVSIM=m
-CONFIG_NET_FOU=m
 CONFIG_MPLS_ROUTING=m
 CONFIG_MPLS_IPTUNNEL=m
 CONFIG_NET_SCH_INGRESS=m