iio: multiplexer: iio-mux: Simplify with dev_err_probe()

Common pattern of handling deferred probe can be simplified with
dev_err_probe().  Less code and also it prints the error value.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Peter Rosin <peda@axentia.se>
Link: https://lore.kernel.org/r/20200829064726.26268-18-krzk@kernel.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/multiplexer/iio-mux.c

@@ -354,11 +354,9 @@ static int mux_probe(struct platform_device *pdev)
 		return -ENODEV;
 
 	parent = devm_iio_channel_get(dev, "parent");
-	if (IS_ERR(parent)) {
-		if (PTR_ERR(parent) != -EPROBE_DEFER)
-			dev_err(dev, "failed to get parent channel\n");
-		return PTR_ERR(parent);
-	}
+	if (IS_ERR(parent))
+		return dev_err_probe(dev, PTR_ERR(parent),
+				     "failed to get parent channel\n");
 
 	sizeof_ext_info = iio_get_channel_ext_info_count(parent);
 	if (sizeof_ext_info) {