remoteproc: imx_rproc: Simplify some error message

dev_err_probe() already prints the error code in a human readable way, so
there is no need to duplicate it as a numerical value at the end of the
message.

While at it, remove 'ret' that is mostly useless.

Fixes: 2df70620 ("remoteproc: imx_proc: enable virtio/mailbox")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/6b9343c2688117a340661d8ee491c2962c54a09a.1659736936.git.christophe.jaillet@wanadoo.frSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/remoteproc/imx_rproc.c

@@ -646,7 +646,6 @@ static int imx_rproc_xtr_mbox_init(struct rproc *rproc)
 	struct imx_rproc *priv = rproc->priv;
 	struct device *dev = priv->dev;
 	struct mbox_client *cl;
-	int ret;
 
 	if (!of_get_property(dev->of_node, "mbox-names", NULL))
 		return 0;
@@ -659,18 +658,15 @@ static int imx_rproc_xtr_mbox_init(struct rproc *rproc)
 	cl->rx_callback = imx_rproc_rx_callback;
 
 	priv->tx_ch = mbox_request_channel_byname(cl, "tx");
-	if (IS_ERR(priv->tx_ch)) {
-		ret = PTR_ERR(priv->tx_ch);
-		return dev_err_probe(cl->dev, ret,
-				     "failed to request tx mailbox channel: %d\n", ret);
-	}
+	if (IS_ERR(priv->tx_ch))
+		return dev_err_probe(cl->dev, PTR_ERR(priv->tx_ch),
+				     "failed to request tx mailbox channel\n");
 
 	priv->rx_ch = mbox_request_channel_byname(cl, "rx");
 	if (IS_ERR(priv->rx_ch)) {
 		mbox_free_channel(priv->tx_ch);
-		ret = PTR_ERR(priv->rx_ch);
-		return dev_err_probe(cl->dev, ret,
-				     "failed to request rx mailbox channel: %d\n", ret);
+		return dev_err_probe(cl->dev, PTR_ERR(priv->rx_ch),
+				     "failed to request rx mailbox channel\n");
 	}
 
 	return 0;