[NET] NETNS: Omit namespace comparision without CONFIG_NET_NS.

Introduce an inline net_eq() to compare two namespaces.
Without CONFIG_NET_NS, since no namespace other than &init_net
exists, it is always 1.

We do not need to convert 1) inline vs inline and
2) inline vs &init_net comparisons.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 923f2b8..f8f3d1a 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -118,6 +118,12 @@
 {
 	atomic_dec(&net->use_count);
 }
+
+static inline
+int net_eq(const struct net *net1, const struct net *net2)
+{
+	return net1 == net2;
+}
 #else
 static inline struct net *get_net(struct net *net)
 {
@@ -141,6 +147,12 @@
 {
 	return net;
 }
+
+static inline
+int net_eq(const struct net *net1, const struct net *net2)
+{
+	return 1;
+}
 #endif
 
 #define for_each_net(VAR)				\