ALSA: hda - Add / fix kernel doc comments

Give some readable comment in kernel doc style for each exported
function, as I promised in the previous meetings.  While we're at it,
fix the wrong comments, too.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/hda/hdac_bus.c b/sound/hda/hdac_bus.c
index 27c447e..0e81ea89 100644
--- a/sound/hda/hdac_bus.c
+++ b/sound/hda/hdac_bus.c
@@ -172,6 +172,15 @@
 	}
 }
 
+/**
+ * snd_hdac_bus_add_device - Add a codec to bus
+ * @bus: HDA core bus
+ * @codec: HDA core device to add
+ *
+ * Adds the given codec to the list in the bus.  The caddr_tbl array
+ * and codec_powered bits are updated, as well.
+ * Returns zero if success, or a negative error code.
+ */
 int snd_hdac_bus_add_device(struct hdac_bus *bus, struct hdac_device *codec)
 {
 	if (bus->caddr_tbl[codec->addr]) {
@@ -188,6 +197,11 @@
 }
 EXPORT_SYMBOL_GPL(snd_hdac_bus_add_device);
 
+/**
+ * snd_hdac_bus_remove_device - Remove a codec from bus
+ * @bus: HDA core bus
+ * @codec: HDA core device to remove
+ */
 void snd_hdac_bus_remove_device(struct hdac_bus *bus,
 				struct hdac_device *codec)
 {