ASoC: mediatek: mt8186: Fix mutex double unlock in GPIO request

The lockdep mechanism revealed an unbalanced unlocking on MT8186:

  [    2.993966] WARNING: bad unlock balance detected!
  [    2.993978] -------------------------------------
  [    2.993983] kworker/u16:1/10 is trying to release lock (gpio_request_mutex) at:
  [    2.993994] [<ffffffdcd9adebf8>] mt8186_afe_gpio_request+0xf8/0x210
  [    2.994012] but there are no more locks to release!

The cause is that the mutex will be double unlocked if dai is unknown
during GPIO selection, and this patch fixes it.

Fixes: cfa9a966 ("ASoC: mediatek: mt8186: support gpio control in platform driver")
Signed-off-by: Fei Shao <fshao@chromium.org>
Link: https://lore.kernel.org/r/20220617111003.2014395-1-fshao@chromium.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/mediatek/mt8186/mt8186-afe-gpio.c

@@ -230,7 +230,6 @@ int mt8186_afe_gpio_request(struct device *dev, bool enable,
 		sel = enable ? MT8186_AFE_GPIO_PCM_ON : MT8186_AFE_GPIO_PCM_OFF;
 		break;
 	default:
-		mutex_unlock(&gpio_request_mutex);
 		dev_err(dev, "%s(), invalid dai %d\n", __func__, dai);
 		goto unlock;
 	}