net: neigh: make ->hh_len 32-bit

Using 16-bit ->hh_len doesn't save any memory, save some .text instead:

	add/remove: 0/0 grow/shrink: 1/6 up/down: 2/-19 (-17)
	function                                     old     new   delta
	neigh_update                                2312    2314      +2
	fwnet_header_cache                           199     197      -2
	eth_header_cache                             101      99      -2
	ip6_finish_output2                          2371    2368      -3
	vrf_finish_output6                          1522    1518      -4
	vrf_finish_output                           1413    1409      -4
	ip_finish_output2                           1627    1623      -4

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -237,8 +237,7 @@ struct netdev_hw_addr_list {
 	netdev_hw_addr_list_for_each(ha, &(dev)->mc)
 
 struct hh_cache {
-	u16		hh_len;
-	u16		__pad;
+	unsigned int	hh_len;
 	seqlock_t	hh_lock;
 
 	/* cached hardware header; allow for machine alignment needs.        */

include/net/neighbour.h

@@ -450,7 +450,7 @@ static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
 static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
 {
 	unsigned int seq;
-	int hh_len;
+	unsigned int hh_len;
 
 	do {
 		seq = read_seqbegin(&hh->hh_lock);
@@ -459,7 +459,7 @@ static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb
 			/* this is inlined by gcc */
 			memcpy(skb->data - HH_DATA_MOD, hh->hh_data, HH_DATA_MOD);
 		} else {
-			int hh_alen = HH_DATA_ALIGN(hh_len);
+			unsigned int hh_alen = HH_DATA_ALIGN(hh_len);
 
 			memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
 		}