ASoC: dmaengine: fix deferred probe detection

Check the return value of dma_request_slave_channel_reason() to see if
deferred probe happens, not the variable the return value will be
assigned to later.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Fixes: 5eda87b ("ASoC: dmaengine: support deferred probe for DMA channels")
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/soc-generic-dmaengine-pcm.c

@@ -321,7 +321,7 @@ static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
 			name = config->chan_names[i];
 		chan = dma_request_slave_channel_reason(dev, name);
 		if (IS_ERR(chan)) {
-			if (PTR_ERR(pcm->chan[i]) == -EPROBE_DEFER)
+			if (PTR_ERR(chan) == -EPROBE_DEFER)
 				return -EPROBE_DEFER;
 			pcm->chan[i] = NULL;
 		} else {