bridge: add new hwmode swdev

Current hwmode settings are "vepa" or "veb".  These are for NIC interfaces
with basic bridging function offloaded to HW.  Add new "swdev" for full
switch device offloads.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_bridge.h

@@ -105,6 +105,7 @@ struct __fdb_entry {
 
 #define BRIDGE_MODE_VEB		0	/* Default loopback mode */
 #define BRIDGE_MODE_VEPA	1	/* 802.1Qbg defined VEPA mode */
+#define BRIDGE_MODE_SWDEV	2	/* Full switch device offload */
 
 /* Bridge management nested attributes
  * [IFLA_AF_SPEC] = {