ASoC: Export devm_snd_soc_register_platform()

devm_snd_soc_register_platform() is used in drivers which can be build as
modules, so it needs to be exported to avoid linkers errors like:

	ERROR: "devm_snd_soc_register_platform" [sound/soc/omap/snd-soc-omap.ko] undefined!
	ERROR: "devm_snd_soc_register_platform" [sound/soc/davinci/snd-soc-davinci.ko] undefined!

Fixes: 8931bf6 ("ASoC: Add resource managed snd_soc_register_platform()")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/soc-devres.c

@@ -85,6 +85,7 @@ int devm_snd_soc_register_platform(struct device *dev,
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(devm_snd_soc_register_platform);
 
 static void devm_card_release(struct device *dev, void *res)
 {