xen/netback: fix incorrect usage of RING_HAS_UNCONSUMED_REQUESTS()

Commit 6fac592 ("xen: update ring.h") missed to fix one use case
of RING_HAS_UNCONSUMED_REQUESTS().

Reported-by: Jan Beulich <[email protected]>
Fixes: 6fac592 ("xen: update ring.h")
Signed-off-by: Juergen Gross <[email protected]>
Reviewed-by: Jan Beulich <[email protected]>
Acked-by: Wei Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: jgross1

drivers/net/xen-netback/netback.c

@@ -828,7 +828,7 @@ static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 			break;
 		}
 
-		work_to_do = RING_HAS_UNCONSUMED_REQUESTS(&queue->tx);
+		work_to_do = XEN_RING_NR_UNCONSUMED_REQUESTS(&queue->tx);
 		if (!work_to_do)
 			break;