net: make struct dst_entry::dev first member

struct dst_entry::dev is used most often. Move it so it can be accessed without imm8 offset on x86_64.

add/remove: 0/0 grow/shrink: 9/239 up/down: 52/-413 (-361)
function old new delta
dst_rcu_free 126 138 +12
fnhe_flush_routes 211 219 +8
rt_set_nexthop 747 754 +7
rt_cache_route 85 91 +6
rt6_release 209 215 +6
dst_release 107 111 +4
dst_destroy_rcu 29 33 +4
dn_dst_check_expire 329 333 +4
dn_insert_route 484 485 +1
xfrm_resolve_and_create_bundle 2991 2990 -1
...
ip_route_me_harder 1163 1157 -6
__ip_append_data.isra 2730 2724 -6
ip6_forward 3052 3045 -7
callforward_do_filter 659 651 -8
dst_gc_task 571 549 -22

---

 include/net/dst.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -31,9 +31,9 @@
 struct sk_buff;
 
 struct dst_entry {
+	struct net_device       *dev;
 	struct rcu_head		rcu_head;
 	struct dst_entry	*child;
-	struct net_device       *dev;
 	struct  dst_ops	        *ops;
 	unsigned long		_metrics;
 	unsigned long           expires;

From: Alexey Dobriyan <[email protected]>
Date: Wed, 17 May 2017 19:31:39 +0300

...

Applied.