ethtool: add compat for flash update

If driver does not support ethtool flash update operation
call into devlink.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -1195,11 +1195,18 @@ devlink_health_report(struct devlink_health_reporter *reporter,
 #if IS_REACHABLE(CONFIG_NET_DEVLINK)
 void devlink_compat_running_version(struct net_device *dev,
 				    char *buf, size_t len);
+int devlink_compat_flash_update(struct net_device *dev, const char *file_name);
 #else
 static inline void
 devlink_compat_running_version(struct net_device *dev, char *buf, size_t len)
 {
 }
+
+static inline int
+devlink_compat_flash_update(struct net_device *dev, const char *file_name)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 #endif /* _NET_DEVLINK_H_ */