libceph: fix double-free of page vector

ceph_release_page_vector() kfrees the vector; we shouldn't do it here too.
Reported-by: Jeff Wu <cpwu@tnsoft.com.cn>
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/addr.c

@@ -345,7 +345,6 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 
 out_pages:
 	ceph_release_page_vector(pages, nr_pages);
-	kfree(pages);
 out:
 	ceph_osdc_put_request(req);
 	return ret;