[media] Docbook: Fix description of struct media_devnode

Warning(.//include/media/media-devnode.h:80): No description found for parameter 'fops'
Warning(.//include/media/media-devnode.h:80): No description found for parameter 'dev'
Warning(.//include/media/media-devnode.h:80): No description found for parameter 'cdev'
Warning(.//include/media/media-devnode.h:80): No description found for parameter 'release'

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>
Acked-by: Jonathan Corbet <[e-mail]>

include/media/media-devnode.h

···
 
 /**
  * struct media_devnode - Media device node
+ * @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
  * @minor:	device node minor number
  * @flags:	flags, combination of the MEDIA_FLAG_* constants
+ * @release:	release callback called at the end of media_devnode_release()
  *
  * This structure represents a media-related device node.
  *