NFS: Fix documenting comment for nfs_create_request()

Clean up: the first parameter of nfs_create_request() has been
incorrectly documented since time immemorial (OK, since before
2.6.12).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pagelist.c

@@ -41,7 +41,7 @@ nfs_page_free(struct nfs_page *p)
 
 /**
  * nfs_create_request - Create an NFS read/write request.
- * @file: file descriptor to use
+ * @ctx: open context to use
  * @inode: inode to which the request is attached
  * @page: page to write
  * @offset: starting offset within the page for the write