net: mdio: mux-mmioreg: Switch to use dev_err_probe() helper

dev_err() can be replace with dev_err_probe() which will check if error
code is -EPROBE_DEFER.

Signed-off-by: Yang Yingliang <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/mdio/mdio-mux-mmioreg.c

···
 	ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
 			    mdio_mux_mmioreg_switch_fn,
 			    &s->mux_handle, s, NULL);
-	if (ret) {
-		if (ret != -EPROBE_DEFER)
-			dev_err(&pdev->dev,
-				"failed to register mdio-mux bus %pOF\n", np);
-		return ret;
-	}
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "failed to register mdio-mux bus %pOF\n", np);
 
 	pdev->dev.platform_data = s;