ceph: use list_move_tail instead of list_del/list_add_tail

#include <linux/module.h>

#include <linux/gfp.h>

#include <linux/pagemap.h>

	ceph_pagelist_unmap_tail(pl);

	while (pl->head.prev != c->page_lru) {

		page = list_entry(pl->head.prev, struct page, lru);

		list_del(&page->lru);                /* remove from pagelist */

		list_add_tail(&page->lru, &pl->free_list); /* add to reserve */

		/* move from pagelist to reserve */

		list_move_tail(&page->lru, &pl->free_list);

		++pl->num_pages_free;

	}

	pl->room = c->room;