power: supply: ab8500: Clean some error messages

There is an useless extra comma at the end of some error messages, remove
them.

Signed-off-by: Christophe JAILLET <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Link: https://lore.kernel.org/r/e7ac0fa83c[e-mail]
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/supply/ab8500_charger.c

···
 		ret = iio_read_channel_processed_scale(di->adc_main_charger_v,
 						       &vch, 1000);
 		if (ret < 0) {
-			dev_err(di->dev, "%s ADC conv failed,\n", __func__);
+			dev_err(di->dev, "%s ADC conv failed\n", __func__);
 			return ret;
 		}
 	} else {
···
 		ret = iio_read_channel_processed_scale(di->adc_vbus_v,
 						       &vch, 1000);
 		if (ret < 0) {
-			dev_err(di->dev, "%s ADC conv failed,\n", __func__);
+			dev_err(di->dev, "%s ADC conv failed\n", __func__);
 			return ret;
 		}
 	} else {
···
 		ret = iio_read_channel_processed_scale(di->adc_usb_charger_c,
 						       &ich, 1000);
 		if (ret < 0) {
-			dev_err(di->dev, "%s ADC conv failed,\n", __func__);
+			dev_err(di->dev, "%s ADC conv failed\n", __func__);
 			return ret;
 		}
 	} else {
···
 		ret = iio_read_channel_processed_scale(di->adc_main_charger_c,
 						       &ich, 1000);
 		if (ret < 0) {
-			dev_err(di->dev, "%s ADC conv failed,\n", __func__);
+			dev_err(di->dev, "%s ADC conv failed\n", __func__);
 			return ret;
 		}
 	} else {