macvlan: Provide function for interfaces to release HW offload

This patch provides a basic function to allow a lower device to disable
macvlan offload if it was previously enabled on a given macvlan. The idea
here is to allow for recovery from failure should the lowerdev run out of
resources.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

include/linux/if_macvlan.h

@@ -97,4 +97,12 @@ static inline bool macvlan_supports_dest_filter(struct net_device *dev)
 	       macvlan->mode == MACVLAN_MODE_VEPA ||
 	       macvlan->mode == MACVLAN_MODE_BRIDGE;
 }
+
+static inline int macvlan_release_l2fw_offload(struct net_device *dev)
+{
+	struct macvlan_dev *macvlan = netdev_priv(dev);
+
+	macvlan->accel_priv = NULL;
+	return dev_uc_add(macvlan->lowerdev, dev->dev_addr);
+}
 #endif /* _LINUX_IF_MACVLAN_H */