ASoC: edma-pcm: Add empty functions for !CONFIG_SND_EDMA_SOC builds

So drivers mixing with other platform drivers, like davinci-mcasp do not
need to fiddle with CONFIG_SND_EDMA_SOC in their code.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/davinci/edma-pcm.h

@@ -20,6 +20,13 @@
 #ifndef __EDMA_PCM_H__
 #define __EDMA_PCM_H__
 
+#if IS_ENABLED(CONFIG_SND_EDMA_SOC)
 int edma_pcm_platform_register(struct device *dev);
+#else
+static inline int edma_pcm_platform_register(struct device *dev)
+{
+	return 0;
+}
+#endif /* CONFIG_SND_EDMA_SOC */
 
 #endif /* __EDMA_PCM_H__ */