net-sysfs: get_netdev_queue_index() cleanup

Redo commit ed1acc8cd8c22efa919da8d300bab646e01c2dce.

Commit 822b3b2ebfff8e9b3d006086c527738a7ca00cd0 ("net: Add max rate tx queue
attribute") moved get_netdev_queue_index around, but kept the old version.
Probably because of a reuse of the original patch from before Eric's change to
that function.

Remove one inline keyword, and no need for a loop to find
an index into a table.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@redhat.com>
Fixes: 822b3b2ebfff ("net: Add max rate tx queue attribute")
Acked-by:  Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/net-sysfs.c

@@ -1004,15 +1004,12 @@ static ssize_t show_trans_timeout(struct netdev_queue *queue,
 }
 
 #ifdef CONFIG_XPS
-static inline unsigned int get_netdev_queue_index(struct netdev_queue *queue)
+static unsigned int get_netdev_queue_index(struct netdev_queue *queue)
 {
 	struct net_device *dev = queue->dev;
-	int i;
-
-	for (i = 0; i < dev->num_tx_queues; i++)
-		if (queue == &dev->_tx[i])
-			break;
+	unsigned int i;
 
+	i = queue - dev->_tx;
 	BUG_ON(i >= dev->num_tx_queues);
 
 	return i;