netfilter: nft_masq: correct length for loading protocol registers

The values in the protocol registers are two bytes wide.  However, when
parsing the register loads, the code currently uses the larger 16-byte
size of a `union nf_inet_addr`.  Change it to use the (correct) size of
a `union nf_conntrack_man_proto` instead.

Fixes: 8a6bf5d ("netfilter: nft_masq: support port range")
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_masq.c

@@ -43,7 +43,7 @@ static int nft_masq_init(const struct nft_ctx *ctx,
 			 const struct nft_expr *expr,
 			 const struct nlattr * const tb[])
 {
-	u32 plen = sizeof_field(struct nf_nat_range, min_addr.all);
+	u32 plen = sizeof_field(struct nf_nat_range, min_proto.all);
 	struct nft_masq *priv = nft_expr_priv(expr);
 	int err;