ASoC: sh: siu_pcm: remove unused variable

cppcheck warning:

sound/soc/sh/siu_pcm.c:225:8: style: Variable 'virt' is assigned a
value that is never used. [unreadVariable]

  virt = PERIOD_OFFSET(rt->dma_area,
       ^

It's not clear what this variable was needed for, remove it.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210219231635.5749-9-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sh/siu_pcm.c

@@ -217,14 +217,10 @@ static void siu_io_work(struct work_struct *work)
 	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
 		dma_addr_t buff;
 		size_t count;
-		u8 *virt;
 
 		buff = (dma_addr_t)PERIOD_OFFSET(rt->dma_addr,
 						siu_stream->cur_period,
 						siu_stream->period_bytes);
-		virt = PERIOD_OFFSET(rt->dma_area,
-				     siu_stream->cur_period,
-				     siu_stream->period_bytes);
 		count = siu_stream->period_bytes;
 
 		/* DMA transfer start */