fscache, cachefiles: Fix checker warnings

Fix a couple of checker warnings in fscache and cachefiles:

 (1) fscache_n_op_requeue is never used, so get rid of it.

 (2) cachefiles_uncache_page() is passed in a lock that it releases, so
     this needs annotating.

Signed-off-by: David Howells <dhowells@redhat.com>

fs/cachefiles/rdwr.c

@@ -952,6 +952,7 @@ error:
  * - cache withdrawal is prevented by the caller
  */
 void cachefiles_uncache_page(struct fscache_object *_object, struct page *page)
+	__releases(&object->fscache.cookie->lock)
 {
 	struct cachefiles_object *object;
 	struct cachefiles_cache *cache;

fs/fscache/stats.c

@@ -21,7 +21,6 @@
 atomic_t fscache_n_op_pend;
 atomic_t fscache_n_op_run;
 atomic_t fscache_n_op_enqueue;
-atomic_t fscache_n_op_requeue;
 atomic_t fscache_n_op_deferred_release;
 atomic_t fscache_n_op_initialised;
 atomic_t fscache_n_op_release;