leds: leds-netxbig: 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strict_strtoul() is obsolete.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>
diff --git a/drivers/leds/leds-netxbig.c b/drivers/leds/leds-netxbig.c
index 461bbf9..c4b482b 100644
--- a/drivers/leds/leds-netxbig.c
+++ b/drivers/leds/leds-netxbig.c
@@ -243,7 +243,7 @@
 	int mode_val;
 	int ret;
 
-	ret = strict_strtoul(buff, 10, &enable);
+	ret = kstrtoul(buff, 10, &enable);
 	if (ret < 0)
 		return ret;