fs/mq_open: revising comments

This contains minor revision on comments of `file_mq_open()`.

Signed-off-by: Yanfeng Liu <[email protected]>

Author: yf13

fs/mqueue/mq_open.c

@@ -393,6 +393,7 @@ static mqd_t nxmq_vopen(FAR const char *mq_name, int oflags, va_list ap)
  *  behavior of this function
  *
  * Input Parameters:
+ *   mq - address of to-be-initialized struct file instance.
  *   mq_name - Name of the queue to open
  *   oflags - open flags
  *   Optional parameters.  When the O_CREAT flag is specified, two optional
@@ -407,7 +408,7 @@ static mqd_t nxmq_vopen(FAR const char *mq_name, int oflags, va_list ap)
  * Returned Value:
  *   This is an internal OS interface and should not be used by applications.
  *   It follows the NuttX internal error return policy:  Zero (OK) is
- *   returned on success, mqdes point to the new message queue descriptor.
+ *   returned on success, instance pointed by mq is also initialized.
  *   A negated errno value is returned on failure.
  *
  ****************************************************************************/