ASoC: amd: raven: acp3x-i2s: fix 'set but not used' warning

Fix W=1 warning. the card variable is useless here
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200702164433.162815-5-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/amd/raven/acp3x-i2s.c

@@ -150,13 +150,11 @@ static int acp3x_i2s_trigger(struct snd_pcm_substream *substream,
 {
 	struct i2s_stream_instance *rtd;
 	struct snd_soc_pcm_runtime *prtd;
-	struct snd_soc_card *card;
 	u32 ret, val, period_bytes, reg_val, ier_val, water_val;
 	u32 buf_size, buf_reg;
 
 	prtd = substream->private_data;
 	rtd = substream->runtime->private_data;
-	card = prtd->card;
 	period_bytes = frames_to_bytes(substream->runtime,
 			substream->runtime->period_size);
 	buf_size = frames_to_bytes(substream->runtime,