drivers/video/backlight/s6e63m0.c: fix corruption storing gamma mode

strict_strtoul() writes a long but ->gamma_mode only has space to store an
int, so on 64 bit systems we end up scribbling over ->gamma_table_count as
well. I've changed it to use kstrtouint() instead.

Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Inki Dae <[e-mail]>
Signed-off-by: Florian Tobias Schandinat <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/video/backlight/s6e63m0.c

···
 	struct backlight_device *bd = NULL;
 	int brightness, rc;
 
-	rc = strict_strtoul(buf, 0, (unsigned long *)&lcd->gamma_mode);
+	rc = kstrtouint(buf, 0, &lcd->gamma_mode);
 	if (rc < 0)
 		return rc;