[media] media-devnode.h: Fix documentation

Two parameters were documented with a wrong name, and a struct
device pointer description was missing.

That caused the following warnings, when building documentation:

include/media/media-devnode.h:102: warning: No description found for parameter 'media_dev'
include/media/media-devnode.h:126: warning: No description found for parameter 'mdev'
include/media/media-devnode.h:126: warning: Excess function parameter 'media_dev' description in 'media_devnode_register'

Rename the description, to match the function parameter and fix
Documentation.

No funcional changes.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

include/media/media-devnode.h

@@ -69,8 +69,9 @@ struct media_file_operations {
 
 /**
  * struct media_devnode - Media device node
+ * @media_dev:	pointer to struct &media_device
  * @fops:	pointer to struct &media_file_operations with media device ops
- * @dev:	struct device pointer for the media controller device
+ * @dev:	pointer to struct &device containing the media controller device
  * @cdev:	struct cdev pointer character device
  * @parent:	parent device
  * @minor:	device node minor number
@@ -107,7 +108,7 @@ struct media_devnode {
 /**
  * media_devnode_register - register a media device node
  *
- * @media_dev: struct media_device we want to register a device node
+ * @mdev: struct media_device we want to register a device node
  * @devnode: media device node structure we want to register
  * @owner: should be filled with %THIS_MODULE
  *