net: update real_num_rx_queues even when !CONFIG_SYSFS

We used to depend on real_num_rx_queues as a upper bound for sanity
checks.  For AF_XDP socket validation it's useful if the check behaves
the same regardless of CONFIG_SYSFS setting.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -3431,8 +3431,9 @@ int netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq);
 int netif_set_real_num_rx_queues(struct net_device *dev, unsigned int rxq);
 #else
 static inline int netif_set_real_num_rx_queues(struct net_device *dev,
-						unsigned int rxq)
+						unsigned int rxqs)
 {
+	dev->real_num_rx_queues = rxqs;
 	return 0;
 }
 #endif