sfc: Make RX queue descriptor counts unsigned for consistency

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index fc6770e..3fd6dbe 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -272,9 +272,9 @@
 	bool enabled;
 	bool flush_pending;
 
-	int added_count;
-	int notified_count;
-	int removed_count;
+	unsigned int added_count;
+	unsigned int notified_count;
+	unsigned int removed_count;
 	unsigned int max_fill;
 	unsigned int fast_fill_trigger;
 	unsigned int min_fill;