leds: ledtrig-gpio: replace strict_strtoul() with kstrtoul()

The usage of strict_strtoul() is not preferred, because
strict_strtoul() is obsolete. Thus, kstrtoul() should be
used.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/ledtrig-gpio.c

@@ -110,7 +110,7 @@ static ssize_t gpio_trig_inverted_store(struct device *dev,
 	unsigned long inverted;
 	int ret;
 
-	ret = strict_strtoul(buf, 10, &inverted);
+	ret = kstrtoul(buf, 10, &inverted);
 	if (ret < 0)
 		return ret;