ASoC: dmaengine: Improve of_node test in dmaengine_pcm_request_chan_of()

Currently when of_node of the "PCM" device is null
dmaengine_pcm_request_chan_of() function will bail out, including cases
when custom DMA device is intended to be used.  To have the channels
properly requested when custom DMA device is provided extend the of_node
test to also consider dma_dev->of_node.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

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

@@ -415,7 +415,8 @@ static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
 
 	if ((pcm->flags & (SND_DMAENGINE_PCM_FLAG_NO_DT |
 			   SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME)) ||
-	    !dev->of_node)
+	     (!dev->of_node && !(config && config->dma_dev &&
+				config->dma_dev->of_node)))
 		return 0;
 
 	if (config && config->dma_dev) {