ASoC: wm8955: harmless underflow in wm8955_put_deemph()

Valid values for "deemph" are zero and one, but we mistakenly allow
negative values as well. It's harmless but we may as well clean it up.

Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Charles Keepax <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/codecs/wm8955.c

···
 {
 	struct snd_soc_codec *codec = snd_soc_kcontrol_codec(kcontrol);
 	struct wm8955_priv *wm8955 = snd_soc_codec_get_drvdata(codec);
-	int deemph = ucontrol->value.integer.value[0];
+	unsigned int deemph = ucontrol->value.integer.value[0];
 
 	if (deemph > 1)
 		return -EINVAL;