bridge: forwarding table information for >256 devices

The forwarding table binary interface (my bad choice), only exposes
the port number of the first 8 bits. The bridge code was limited to
256 ports at the time, but now the kernel supports up 1024 ports, so
the upper bits are lost when doing:

   brctl showmacs

The fix is to squeeze the extra bits into small hole left in data
structure, to maintain binary compatiablity.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 58e43e5..950e13d 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -97,7 +97,9 @@
 	__u8 port_no;
 	__u8 is_local;
 	__u32 ageing_timer_value;
-	__u32 unused;
+	__u8 port_hi;
+	__u8 pad0;
+	__u16 unused;
 };
 
 #ifdef __KERNEL__