netfilter: ipset: add the missing IP_SET_HASH_WITH_NET0 macro for ip_set_hash_netportnet.c

The missing IP_SET_HASH_WITH_NET0 macro in ip_set_hash_netportnet can
lead to the use of wrong `CIDR_POS(c)` for calculating array offsets,
which can lead to integer underflow. As a result, it leads to slab
out-of-bound access.
This patch adds back the IP_SET_HASH_WITH_NET0 macro to
ip_set_hash_netportnet to address the issue.

Fixes: 886503f34d63 ("netfilter: ipset: actually allow allowable CIDR 0 in hash:net,port,net")
Suggested-by: Jozsef Kadlecsik <[e-mail]>
Signed-off-by: Kyle Zeng <[e-mail]>
Acked-by: Jozsef Kadlecsik <[e-mail]>
Signed-off-by: Florian Westphal <[e-mail]>

net/netfilter/ipset/ip_set_hash_netportnet.c

···
 #define IP_SET_HASH_WITH_PROTO
 #define IP_SET_HASH_WITH_NETS
 #define IPSET_NET_COUNT 2
+#define IP_SET_HASH_WITH_NET0
 
 /* IPv4 variant */