ALSA: hda - Fix another cache list management

Fix another silly bug in the amp cache list management.

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 a73f0eb..ee122b0 100644
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -539,6 +539,16 @@
 	array->alloc_align = align;
 }
 
+static inline void *snd_array_elem(struct snd_array *array, unsigned int idx)
+{
+	return array->list + idx * array->elem_size;
+}
+
+static inline unsigned int snd_array_index(struct snd_array *array, void *ptr)
+{
+	return (unsigned long)(ptr - array->list) / array->elem_size;
+}
+
 /*
  * Structures
  */