libceph: remove redundant declaration

ceph_release_page_vector was defined twice in libceph.h
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>

include/linux/ceph/libceph.h

@@ -211,7 +211,6 @@ extern struct page **ceph_get_direct_page_vector(const void __user *data,
 						 bool write_page);
 extern void ceph_put_page_vector(struct page **pages, int num_pages,
 				 bool dirty);
-extern void ceph_release_page_vector(struct page **pages, int num_pages);
 extern struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags);
 extern int ceph_copy_user_to_page_vector(struct page **pages,
 					 const void __user *data,