tcp/dccp: cache line align inet_hashinfo

I have seen tcp_hashinfo starting at a non optimal location,
forcing input handlers to pull two cache lines instead of one,
and sharing a cache line that was dirtied more than necessary:

ffffffff83680600 b tcp_orphan_timer
ffffffff83680628 b tcp_orphan_cache
ffffffff8368062c b tcp_enable_tx_delay.__tcp_tx_delay_enabled
ffffffff83680630 B tcp_hashinfo
ffffffff83680680 b tcp_cong_list_lock

After this patch, ehash, ehash_locks, ehash_mask and ehash_locks_mask
are located in a read-only cache line.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_hashtables.h

@@ -177,7 +177,7 @@ struct inet_hashinfo {
 	struct inet_listen_hashbucket	*lhash2;
 
 	bool				pernet;
-};
+} ____cacheline_aligned_in_smp;
 
 static inline struct inet_hashinfo *tcp_or_dccp_get_hashinfo(const struct sock *sk)
 {