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/include/sound/core.h b/include/sound/core.h
index a63680b..5bfe513 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -229,7 +229,7 @@
  * This function uses the card's device pointer to link to the
  * correct &struct device.
  *
- * Returns zero if successful, or a negative error code on failure.
+ * Return: Zero if successful, or a negative error code on failure.
  */
 static inline int snd_register_device(int type, struct snd_card *card, int dev,
 				      const struct file_operations *f_ops,