include/linux/netdevice.h: don't export MAX_HEADER to userspace

Due to the CONFIG_'s the value is anyway not correct in userspace.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -88,6 +88,8 @@ struct wireless_dev;
 #define NETDEV_TX_BUSY 1	/* driver tx path was busy*/
 #define NETDEV_TX_LOCKED -1	/* driver tx lock was already taken */
 
+#ifdef  __KERNEL__
+
 /*
  *	Compute the worst case header length according to the protocols
  *	used.
@@ -114,6 +116,8 @@ struct wireless_dev;
 #define MAX_HEADER (LL_MAX_HEADER + 48)
 #endif
 
+#endif  /*  __KERNEL__  */
+
 struct net_device_subqueue
 {
 	/* Give a control state for each queue.  This struct may contain