fs: update kernel-doc for vfs_rename()

Commit 9fe6145 ("namei: introduce struct renamedata") introduces a
new struct for vfs_rename() and makes the vfs_rename() kernel-doc argument
description out of sync.

Move the description of arguments for vfs_rename() to a new kernel-doc for
the struct renamedata to make these descriptions checkable against the
actual implementation.

Link: https://lore.kernel.org/r/20210204180059.28360-3-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Author: Christian Brauner

include/linux/fs.h

@@ -1782,6 +1782,17 @@ int vfs_rmdir(struct user_namespace *, struct inode *, struct dentry *);
 int vfs_unlink(struct user_namespace *, struct inode *, struct dentry *,
 	       struct inode **);
 
+/**
+ * struct renamedata - contains all information required for renaming
+ * @old_mnt_userns:    old user namespace of the mount the inode was found from
+ * @old_dir:           parent of source
+ * @old_dentry:                source
+ * @new_mnt_userns:    new user namespace of the mount the inode was found from
+ * @new_dir:           parent of destination
+ * @new_dentry:                destination
+ * @delegated_inode:   returns an inode needing a delegation break
+ * @flags:             rename flags
+ */
 struct renamedata {
 	struct user_namespace *old_mnt_userns;
 	struct inode *old_dir;