iio: light: gp2ap002: Drop unneeded explicit casting

The unnecessary explicit casting is being used. Drop it for good.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210312134903.4296-1-andriy.shevchenko@linux.intel.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/gp2ap002.c

@@ -465,8 +465,7 @@ static int gp2ap002_probe(struct i2c_client *client,
 
 	regmap = devm_regmap_init(dev, &gp2ap002_regmap_bus, dev, &config);
 	if (IS_ERR(regmap)) {
-		dev_err(dev, "Failed to register i2c regmap %d\n",
-			(int)PTR_ERR(regmap));
+		dev_err(dev, "Failed to register i2c regmap %ld\n", PTR_ERR(regmap));
 		return PTR_ERR(regmap);
 	}
 	gp2ap002->map = regmap;