[media] media-devnode.h: document the remaining struct/functions

There is one struct and two functions that were not documented.
Add the corresponding kernel-doc documentation for them.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

include/media/media-devnode.h

@@ -40,6 +40,20 @@
  */
 #define MEDIA_FLAG_REGISTERED	0
 
+/**
+ * struct media_file_operations - Media device file operations
+ *
+ * @owner: should be filled with %THIS_MODULE
+ * @read: pointer to the function that implements read() syscall
+ * @write: pointer to the function that implements write() syscall
+ * @poll: pointer to the function that implements poll() syscall
+ * @ioctl: pointer to the function that implements ioctl() syscall
+ * @compat_ioctl: pointer to the function that will handle 32 bits userspace
+ *	calls to the the ioctl() syscall on a Kernel compiled with 64 bits.
+ * @open: pointer to the function that implements open() syscall
+ * @release: pointer to the function that will release the resources allocated
+ *	by the @open function.
+ */
 struct media_file_operations {
 	struct module *owner;
 	ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
@@ -53,7 +67,7 @@ struct media_file_operations {
 
 /**
  * struct media_devnode - Media device node
- * @fops:	pointer to struct media_file_operations with media device ops
+ * @fops:	pointer to struct &media_file_operations with media device ops
  * @dev:	struct device pointer for the media controller device
  * @cdev:	struct cdev pointer character device
  * @parent:	parent device
@@ -117,11 +131,22 @@ int __must_check media_devnode_register(struct media_devnode *mdev,
  */
 void media_devnode_unregister(struct media_devnode *mdev);
 
+/**
+ * media_devnode_data - returns a pointer to the &media_devnode
+ *
+ * @filp: pointer to struct &file
+ */
 static inline struct media_devnode *media_devnode_data(struct file *filp)
 {
 	return filp->private_data;
 }
 
+/**
+ * media_devnode_is_registered - returns true if &media_devnode is registered;
+ *	false otherwise.
+ *
+ * @mdev: pointer to struct &media_devnode.
+ */
 static inline int media_devnode_is_registered(struct media_devnode *mdev)
 {
 	return test_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);