ASoC: Check return value of strict_strtoul() in WM8962

strict_strtoul() has been made __must_check so do so.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>

sound/soc/codecs/wm8962.c

@@ -3500,8 +3500,11 @@ static ssize_t wm8962_beep_set(struct device *dev,
 {
 	struct wm8962_priv *wm8962 = dev_get_drvdata(dev);
 	long int time;
+	int ret;
 
-	strict_strtol(buf, 10, &time);
+	ret = strict_strtol(buf, 10, &time);
+	if (ret != 0)
+		return ret;
 
 	input_event(wm8962->beep, EV_SND, SND_TONE, time);