iio: afe: iio-rescale: 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 <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Acked-by: Peter Rosin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/afe/iio-rescale.c

···
 	int ret;
 
 	source = devm_iio_channel_get(dev, NULL);
-	if (IS_ERR(source)) {
-		if (PTR_ERR(source) != -EPROBE_DEFER)
-			dev_err(dev, "failed to get source channel\n");
-		return PTR_ERR(source);
-	}
+	if (IS_ERR(source))
+		return dev_err_probe(dev, PTR_ERR(source),
+				     "failed to get source channel\n");
 
 	sizeof_ext_info = iio_get_channel_ext_info_count(source);
 	if (sizeof_ext_info) {