netfilter: nf_nat: make unique_tuple return void

The only user of unique_tuple() get_unique_tuple() doesn't care about the
return value of unique_tuple(), so make unique_tuple() return void (nothing).

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/ipv4/netfilter/nf_nat_proto_tcp.c b/net/ipv4/netfilter/nf_nat_proto_tcp.c
index 399e2cf..aa460a5 100644
--- a/net/ipv4/netfilter/nf_nat_proto_tcp.c
+++ b/net/ipv4/netfilter/nf_nat_proto_tcp.c
@@ -20,14 +20,13 @@
 
 static u_int16_t tcp_port_rover;
 
-static bool
+static void
 tcp_unique_tuple(struct nf_conntrack_tuple *tuple,
 		 const struct nf_nat_range *range,
 		 enum nf_nat_manip_type maniptype,
 		 const struct nf_conn *ct)
 {
-	return nf_nat_proto_unique_tuple(tuple, range, maniptype, ct,
-					 &tcp_port_rover);
+	nf_nat_proto_unique_tuple(tuple, range, maniptype, ct, &tcp_port_rover);
 }
 
 static bool