[NET]: Remove HIPPI private from skbuff.h

This removes the private element from skbuff, that is only used by
HIPPI. Instead it uses skb->cb[] to hold the additional data that is
needed in the output path from hard_header to device driver.

PS: The only qdisc that might potentially corrupt this cb[] is if
netem was used over HIPPI. I will take care of that by fixing netem
to use skb->stamp. I don't expect many users of netem over HIPPI

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/hippidevice.h

@@ -26,6 +26,11 @@
 #include <linux/if_hippi.h>
 
 #ifdef __KERNEL__
+
+struct hippi_cb {
+	__u32	ifield;
+};
+
 extern unsigned short hippi_type_trans(struct sk_buff *skb,
 				       struct net_device *dev);