net: aquantia: fix error handling in aq_ptp_poll

Fix currenty ignored returned error by properly checking *err* after
calling aq_nic->aq_hw_ops->hw_ring_hwts_rx_fill().

Addresses-Coverity-ID: 1487357 ("Unused value")
Fixes: 04a18399 ("net: aquantia: implement data PTP datapath")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: NIgor Russkikh <irusskikh@marvell.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -678,6 +678,8 @@ static int aq_ptp_poll(struct napi_struct *napi, int budget)
 
 		err = aq_nic->aq_hw_ops->hw_ring_hwts_rx_fill(aq_nic->aq_hw,
 							      &aq_ptp->hwts_rx);
+		if (err < 0)
+			goto err_exit;
 
 		was_cleaned = true;
 	}