ASoC: am3517evm: Remove unused cpu_dai from hw_params

cpu_dai is not in use in this function and just generates warning at
compile time.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/omap/am3517evm.c

@@ -41,7 +41,6 @@ static int am3517evm_hw_params(struct snd_pcm_substream *substream,
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_soc_dai *codec_dai = rtd->codec_dai;
-	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
 	int ret;
 
 	/* Set the codec system clock for DAC and ADC */