e1000: fix skb truesize underestimation

e1000 allocates a full page per skb fragment. We must account PAGE_SIZE
increments on skb->truesize, not the actual frag length.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/e1000/e1000_main.c

@@ -3737,7 +3737,7 @@ static void e1000_consume_page(struct e1000_buffer *bi, struct sk_buff *skb,
 	bi->page = NULL;
 	skb->len += length;
 	skb->data_len += length;
-	skb->truesize += length;
+	skb->truesize += PAGE_SIZE;
 }
 
 /**