ASoC: Add sound card directory under debugfs/asoc/

There will be need to have sound card specific debugfs entries. This patch
introduces a new debugfs/asoc/{card->name}/ directory but does not add yet
any entries there.

Signed-off-by: Jarkko Nikula <jhnikula@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/sound/soc.h b/include/sound/soc.h
index b048e08..95ce0dd 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -589,6 +589,10 @@
 	struct list_head codec_dev_list;
 	struct list_head platform_dev_list;
 	struct list_head dai_dev_list;
+
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *debugfs_card_root;
+#endif
 };
 
 /* SoC machine DAI configuration, glues a codec and cpu DAI together */