ethernet: aquantia: fix dma_mapping_error test

dma_mapping_error() returns 1 if there is an error and 0 if not.

Fixes: 018423e9 ("net: ethernet: aquantia: Add ring support code")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_ring.c

@@ -298,9 +298,10 @@ int aq_ring_rx_fill(struct aq_ring_s *self)
 					buff->page, 0,
 					AQ_CFG_RX_FRAME_MAX, DMA_FROM_DEVICE);
 
-		err = dma_mapping_error(aq_nic_get_dev(self->aq_nic), buff->pa);
-		if (err < 0)
+		if (dma_mapping_error(aq_nic_get_dev(self->aq_nic), buff->pa)) {
+			err = -ENOMEM;
 			goto err_exit;
+		}
 
 		buff = NULL;
 	}