net: break include loop netdevice.h, dsa.h, devlink.h

There is an include loop between netdevice.h, dsa.h, devlink.h because
of NETDEV_ALIGN, making it impossible to use devlink structures in
dsa.h.

Break this loop by taking dsa.h out of netdevice.h, add a forward
declaration of dsa_switch_tree and netdev_set_default_ethtool_ops()
function, which is what netdevice.h requires.

No longer having dsa.h in netdevice.h means the includes in dsa.h no
longer get included. This breaks a few other files which depend on
these includes. Add these directly in the affected file.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index b7365b58..cc07c3b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -41,7 +41,6 @@
 
 #include <linux/ethtool.h>
 #include <net/net_namespace.h>
-#include <net/dsa.h>
 #ifdef CONFIG_DCB
 #include <net/dcbnl.h>
 #endif
@@ -57,6 +56,8 @@
 struct netpoll_info;
 struct device;
 struct phy_device;
+struct dsa_switch_tree;
+
 /* 802.11 specific */
 struct wireless_dev;
 /* 802.15.4 specific */
@@ -2004,15 +2005,6 @@ void dev_net_set(struct net_device *dev, struct net *net)
 	write_pnet(&dev->nd_net, net);
 }
 
-static inline bool netdev_uses_dsa(struct net_device *dev)
-{
-#if IS_ENABLED(CONFIG_NET_DSA)
-	if (dev->dsa_ptr != NULL)
-		return dsa_uses_tagged_protocol(dev->dsa_ptr);
-#endif
-	return false;
-}
-
 /**
  *	netdev_priv - access network device private data
  *	@dev: network device
diff --git a/include/net/dsa.h b/include/net/dsa.h
index e42897f..f80e819 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -468,6 +468,15 @@ static inline bool dsa_uses_tagged_protocol(struct dsa_switch_tree *dst)
 	return dst->rcv != NULL;
 }
 
+static inline bool netdev_uses_dsa(struct net_device *dev)
+{
+#if IS_ENABLED(CONFIG_NET_DSA)
+	if (dev->dsa_ptr != NULL)
+		return dsa_uses_tagged_protocol(dev->dsa_ptr);
+#endif
+	return false;
+}
+
 struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n);
 void dsa_unregister_switch(struct dsa_switch *ds);
 int dsa_register_switch(struct dsa_switch *ds, struct device *dev);