bonding: add downdelay netlink support

Add IFLA_BOND_DOWNDELAY to allow get/set of bonding parameter
downdelay via netlink.

Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 7588c81..f955067 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -333,6 +333,7 @@
 	IFLA_BOND_ACTIVE_SLAVE,
 	IFLA_BOND_MIIMON,
 	IFLA_BOND_UPDELAY,
+	IFLA_BOND_DOWNDELAY,
 	__IFLA_BOND_MAX,
 };