ASoC: fsl: fsl_dma: remove unused variable

cppcheck warning:

sound/soc/fsl/fsl_dma.c:411:10: style: Variable 'channel' is assigned
a value that is never used. [unreadVariable]

 channel = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1;
         ^

Removing this line shows the variable isn't needed any longer so
remove declaration as well.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210219232937.6440-3-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_dma.c

@@ -392,7 +392,6 @@ static int fsl_dma_open(struct snd_soc_component *component,
 	dma_addr_t ld_buf_phys;
 	u64 temp_link;  	/* Pointer to next link descriptor */
 	u32 mr;
-	unsigned int channel;
 	int ret = 0;
 	unsigned int i;
 
@@ -408,8 +407,6 @@ static int fsl_dma_open(struct snd_soc_component *component,
 		return ret;
 	}
 
-	channel = substream->stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1;
-
 	if (dma->assigned) {
 		dev_err(dev, "dma channel already assigned\n");
 		return -EBUSY;