dpaa2-eth: Use PTR_ERR_OR_ZERO where appropriate

Use PTR_ERR_OR_ZERO instead of PTR_ERR in cases where
zero is a valid input. Reported by smatch.
Signed-off-by: NIoana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -1972,7 +1972,7 @@ alloc_channel(struct dpaa2_eth_priv *priv)
 
 	channel->dpcon = setup_dpcon(priv);
 	if (IS_ERR_OR_NULL(channel->dpcon)) {
-		err = PTR_ERR(channel->dpcon);
+		err = PTR_ERR_OR_ZERO(channel->dpcon);
 		goto err_setup;
 	}
 
@@ -2028,7 +2028,7 @@ static int setup_dpio(struct dpaa2_eth_priv *priv)
 		/* Try to allocate a channel */
 		channel = alloc_channel(priv);
 		if (IS_ERR_OR_NULL(channel)) {
-			err = PTR_ERR(channel);
+			err = PTR_ERR_OR_ZERO(channel);
 			if (err != -EPROBE_DEFER)
 				dev_info(dev,
 					 "No affine channel for cpu %d and above\n", i);