netfilter: nf_tables: Support auto-loading for inet nat

Trying to create an inet family nat chain would not cause
nft_chain_nat.ko module to auto-load due to missing module alias. Add a
proper one with hard-coded family value 1 for the pseudo-family
NFPROTO_INET.

Fixes: d164385e ("netfilter: nat: add inet family nat support")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_chain_nat.c

@@ -142,3 +142,6 @@ MODULE_ALIAS_NFT_CHAIN(AF_INET, "nat");
 #ifdef CONFIG_NF_TABLES_IPV6
 MODULE_ALIAS_NFT_CHAIN(AF_INET6, "nat");
 #endif
+#ifdef CONFIG_NF_TABLES_INET
+MODULE_ALIAS_NFT_CHAIN(1, "nat");	/* NFPROTO_INET */
+#endif