update if_bridge

Use current upstream header.
diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index d2de4e6..ed6868e 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -15,6 +15,7 @@
 
 #include <linux/types.h>
 #include <linux/if_ether.h>
+#include <linux/in6.h>
 
 #define SYSFS_BRIDGE_ATTR	"bridge"
 #define SYSFS_BRIDGE_FDB	"brforward"