ceph: fix comment, remove extraneous args

The offset/length arguments aren't used.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index f22b2e9..9e76d35 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -227,8 +227,7 @@
 extern void ceph_release_page_vector(struct page **pages, int num_pages);
 
 extern struct page **ceph_get_direct_page_vector(const char __user *data,
-					    int num_pages,
-					    loff_t off, size_t len);
+						 int num_pages);
 extern void ceph_put_page_vector(struct page **pages, int num_pages);
 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);