ASoC: spear: spdif_out: Staticize unexported function

The spdif_soc_dai_probe function is only used in spdif_out.c, so make it static.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Rajeev Kumar <rajeev-dlh.kumar@st.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/spear/spdif_out.c

@@ -240,7 +240,7 @@ static const struct snd_kcontrol_new spdif_out_controls[] = {
 			spdif_mute_get, spdif_mute_put),
 };
 
-int spdif_soc_dai_probe(struct snd_soc_dai *dai)
+static int spdif_soc_dai_probe(struct snd_soc_dai *dai)
 {
 	struct spdif_out_dev *host = snd_soc_dai_get_drvdata(dai);