ASoC: wm8904: harmless underflow in wm8904_put_deemph()

We try to check that "deemph" is zero or one, but because of an
underflow bug, it can also be negative. It's fine, negative values are
handled as non-zero. But it's messy and static checkers complain so
let's fix it.

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

sound/soc/codecs/wm8904.c

···
 {
 	struct snd_soc_codec *codec = snd_soc_kcontrol_codec(kcontrol);
 	struct wm8904_priv *wm8904 = 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;