ALSA: hda - Protect user-defined arrays via mutex

The pincfgs, init_verbs and hints set by sysfs or patch might be
changed dynamically on the fly, thus we need to protect it.
Add a simple protection via a mutex.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/hda_codec.h b/sound/pci/hda/hda_codec.h
index 4c4f166..61085b3 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -845,6 +845,7 @@
 	struct snd_array cvt_setups;	/* audio convert setups */
 
 #ifdef CONFIG_SND_HDA_HWDEP
+	struct mutex user_mutex;
 	struct snd_hwdep *hwdep;	/* assigned hwdep device */
 	struct snd_array init_verbs;	/* additional init verbs */
 	struct snd_array hints;		/* additional hints */