inet: remove old fragmentation hash initializing

All fragmentation hash secrets now get initialized by their
corresponding hash function with net_get_random_once. Thus we can
eliminate the initial seeding.

Also provide a comment that hash secret seeding happens at the first
call to the corresponding hashing function.

Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index bfcbc00..6f59de9 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -64,6 +64,10 @@
 	rwlock_t		lock ____cacheline_aligned_in_smp;
 	int			secret_interval;
 	struct timer_list	secret_timer;
+
+	/* The first call to hashfn is responsible to initialize
+	 * rnd. This is best done with net_get_random_once.
+	 */
 	u32			rnd;
 	int			qsize;