ALSA: hda: tegra: Fix unused variable compile warning

Forgot to remove the variable declaration as well in the last commit.
  sound/pci/hda/hda_tegra.c: In function 'hda_tegra_runtime_suspend':
  sound/pci/hda/hda_tegra.c:169:19: warning: unused variable 'bus' [-Wunused-variable]

Fixes: f36da940 ("ALSA: hda: Support PCM sync_stop")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20191212080518.6522-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_tegra.c

@@ -166,7 +166,6 @@ static int __maybe_unused hda_tegra_runtime_suspend(struct device *dev)
 	struct snd_card *card = dev_get_drvdata(dev);
 	struct azx *chip = card->private_data;
 	struct hda_tegra *hda = container_of(chip, struct hda_tegra, chip);
-	struct hdac_bus *bus = azx_bus(chip);
 
 	if (chip && chip->running) {
 		azx_stop_chip(chip);