net: switchdev: add SET_SWITCHDEV_OPS helper

Add a helper to allow switchdev ops to be set if NET_SWITCHDEV is configured
and do nothing otherwise. This allows for slightly cleaner code which
uses switchdev but does not select NET_SWITCHDEV.
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Acked-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/switchdev.h

@@ -217,6 +217,8 @@ void switchdev_port_fwd_mark_set(struct net_device *dev,
 
 bool switchdev_port_same_parent_id(struct net_device *a,
 				   struct net_device *b);
+
+#define SWITCHDEV_SET_OPS(netdev, ops) ((netdev)->switchdev_ops = (ops))
 #else
 
 static inline void switchdev_deferred_process(void)
@@ -322,6 +324,8 @@ static inline bool switchdev_port_same_parent_id(struct net_device *a,
 	return false;
 }
 
+#define SWITCHDEV_SET_OPS(netdev, ops) do {} while (0)
+
 #endif
 
 #endif /* _LINUX_SWITCHDEV_H_ */