dpaa2-eth: Fix passing zero to 'PTR_ERR' warning

Fix smatch warning:

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c:2419
 alloc_channel() warn: passing zero to 'ERR_PTR'

setup_dpcon() should return ERR_PTR(err) instead of zero in error
handling case.

Fixes: d7f5a9d8 ("dpaa2-eth: defer probe on object allocate")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -2370,7 +2370,7 @@ static struct fsl_mc_device *setup_dpcon(struct dpaa2_eth_priv *priv)
 free:
 	fsl_mc_object_free(dpcon);
 
-	return NULL;
+	return ERR_PTR(err);
 }
 
 static void free_dpcon(struct dpaa2_eth_priv *priv,
@@ -2394,8 +2394,8 @@ alloc_channel(struct dpaa2_eth_priv *priv)
 		return NULL;
 
 	channel->dpcon = setup_dpcon(priv);
-	if (IS_ERR_OR_NULL(channel->dpcon)) {
-		err = PTR_ERR_OR_ZERO(channel->dpcon);
+	if (IS_ERR(channel->dpcon)) {
+		err = PTR_ERR(channel->dpcon);
 		goto err_setup;
 	}