[NET]: Remove no longer relevant comment in loopback driver.

It talks about __get_cpu_var() which the driver no longer
does.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 0f9d8c6..f11120b 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -154,7 +154,6 @@
 #endif
 	dev->last_rx = jiffies;
 
-	/* it's OK to use __get_cpu_var() because BHs are off */
 	pcpu_lstats = netdev_priv(dev);
 	lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
 	lb_stats->bytes += skb->len;