fscache: fix missing kerneldoc annotation

.. and make kerneldoc scripts happy.
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

include/linux/fscache.h

@@ -454,6 +454,7 @@ int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
  * @cookie: The cookie representing the cache object
  * @mapping: The netfs inode mapping to which the pages will be attached
  * @pages: A list of potential netfs pages to be filled
+ * @nr_pages: Number of pages to be read and/or allocated
  * @end_io_func: The callback to invoke when and if each page is filled
  * @context: An arbitrary piece of data to pass on to end_io_func()
  * @gfp: The conditions under which memory allocation should be made