ALSA: add/change some comments describing function return values

script/kernel-doc reports the following type of warnings (when run in verbose
mode):

Warning(sound/core/init.c:152): No description found for return value of
'snd_card_create'

To fix that:
- add missing descriptions of function return values
- use "Return:" sections to describe those return values

Along the way:
- complete some descriptions
- fix some typos

Signed-off-by: Yacine Belkadi <yacine.belkadi.1@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/init.c b/sound/core/init.c
index 7b012d1..6ef0640 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -144,7 +144,7 @@
  *  space for the driver to use freely.  The allocated struct is stored
  *  in the given card_ret pointer.
  *
- *  Returns zero if successful or a negative error code.
+ *  Return: Zero if successful or a negative error code.
  */
 int snd_card_create(int idx, const char *xid,
 		    struct module *module, int extra_size,
@@ -337,7 +337,7 @@
  *
  *  Disconnects all APIs from the file-operations (user space).
  *
- *  Returns zero, otherwise a negative error code.
+ *  Return: Zero, otherwise a negative error code.
  *
  *  Note: The current implementation replaces all active file->f_op with special
  *        dummy file operations (they do nothing except release).
@@ -415,7 +415,7 @@
  *  devices automatically.  That is, you don't have to release the devices
  *  by yourself.
  *
- *  Returns zero. Frees all associated devices and frees the control
+ *  Return: Zero. Frees all associated devices and frees the control
  *  interface associated to given soundcard.
  */
 static int snd_card_do_free(struct snd_card *card)
@@ -677,7 +677,7 @@
  *  external accesses.  Thus, you should call this function at the end
  *  of the initialization of the card.
  *
- *  Returns zero otherwise a negative error code if the registration failed.
+ *  Return: Zero otherwise a negative error code if the registration failed.
  */
 int snd_card_register(struct snd_card *card)
 {
@@ -849,7 +849,7 @@
  *  This function adds the component id string to the supported list.
  *  The component can be referred from the alsa-lib.
  *
- *  Returns zero otherwise a negative error code.
+ *  Return: Zero otherwise a negative error code.
  */
   
 int snd_component_add(struct snd_card *card, const char *component)
@@ -883,7 +883,7 @@
  *  This linked-list is used to keep tracking the connection state,
  *  and to avoid the release of busy resources by hotplug.
  *
- *  Returns zero or a negative error code.
+ *  Return: zero or a negative error code.
  */
 int snd_card_file_add(struct snd_card *card, struct file *file)
 {
@@ -920,7 +920,7 @@
  *  called beforehand, it processes the pending release of
  *  resources.
  *
- *  Returns zero or a negative error code.
+ *  Return: Zero or a negative error code.
  */
 int snd_card_file_remove(struct snd_card *card, struct file *file)
 {
@@ -959,6 +959,8 @@
  *
  *  Waits until the power-state is changed.
  *
+ *  Return: Zero if successful, or a negative error code.
+ *
  *  Note: the power lock must be active before call.
  */
 int snd_power_wait(struct snd_card *card, unsigned int power_state)