ASoC: Fix null string usage with WM8753 DAIs

The WM8753 driver multiplexes the DAI structures it exposes to the
outside world, leaving them uninitialised until the codec probes.  Since
the DAI name is used during the registration and setup process provide a
dummy name.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm8753.c

@@ -1451,7 +1451,14 @@ static const struct snd_soc_dai wm8753_all_dai[] = {
 },
 };
 
-struct snd_soc_dai wm8753_dai[2];
+struct snd_soc_dai wm8753_dai[] = {
+	{
+		.name = "WM8753 DAI 0",
+	},
+	{
+		.name = "WM8753 DAI 1",
+	},
+};
 EXPORT_SYMBOL_GPL(wm8753_dai);
 
 static void wm8753_set_dai_mode(struct snd_soc_codec *codec, unsigned int mode)