[IPSEC]: Make x->lastused an unsigned long

Currently x->lastused is u64 which means that it cannot be
read/written atomically on all architectures. David Miller observed
that the value stored in it is only an unsigned long which is always
atomic.

So based on his suggestion this patch changes the internal
representation from u64 to unsigned long while the user-interface
still refers to it as u64.

Signed-off-by: Herbert Xu <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/xfrm.h

···
 	struct timer_list	timer;
 
 	/* Last used time */
-	u64			lastused;
+	unsigned long		lastused;
 
 	/* Reference to data common to all the instances of this
 	 * transformer. */

net/ipv6/xfrm6_mode_ro.c

···
 	__skb_pull(skb, hdr_len);
 	memmove(ipv6_hdr(skb), iph, hdr_len);
 
-	spin_lock_bh(&x->lock);
 	x->lastused = get_seconds();
-	spin_unlock_bh(&x->lock);
 
 	return 0;
 }

net/xfrm/xfrm_user.c

···
 	if (x->coaddr)
 		l += nla_total_size(sizeof(*x->coaddr));
 
-	/* Must count this as this may become non-zero behind our back. */
-	l += nla_total_size(sizeof(x->lastused));
+	/* Must count x->lastused as it may become non-zero behind our back. */
+	l += nla_total_size(sizeof(u64));
 
 	return l;
 }