drm/exynos: use __free_page() to deallocate memory

this patch uses __free_page() to deallocate the pages allocated
by alloc_page() and the pages doesn't need set_parge_dirty()
and mark_page_accessed() because they aren't from page cache so
removes them.

this patch has a pair with previous patch below,
	http://www.spinics.net/lists/dri-devel/msg24382.html

Changelog v2:
remove unnecessary arguments.

Changelog v3:
fix npages type.
- npages can have negative value.
Signed-off-by: NInki Dae <inki.dae@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_gem.c

@@ -126,23 +126,14 @@ struct page **exynos_gem_get_pages(struct drm_gem_object *obj,
 }
 
 static void exynos_gem_put_pages(struct drm_gem_object *obj,
-					struct page **pages,
-					bool dirty, bool accessed)
+					struct page **pages)
 {
-	int i, npages;
+	int npages;
 
 	npages = obj->size >> PAGE_SHIFT;
 
-	for (i = 0; i < npages; i++) {
-		if (dirty)
-			set_page_dirty(pages[i]);
-
-		if (accessed)
-			mark_page_accessed(pages[i]);
-
-		/* Undo the reference we took when populating the table */
-		page_cache_release(pages[i]);
-	}
+	while (--npages >= 0)
+		__free_page(pages[npages]);
 
 	drm_free_large(pages);
 }
@@ -222,7 +213,7 @@ static int exynos_drm_gem_get_pages(struct drm_gem_object *obj)
 	kfree(buf->sgt);
 	buf->sgt = NULL;
 err:
-	exynos_gem_put_pages(obj, pages, true, false);
+	exynos_gem_put_pages(obj, pages);
 	return ret;
 
 }
@@ -240,7 +231,7 @@ static void exynos_drm_gem_put_pages(struct drm_gem_object *obj)
 	kfree(buf->sgt);
 	buf->sgt = NULL;
 
-	exynos_gem_put_pages(obj, buf->pages, true, false);
+	exynos_gem_put_pages(obj, buf->pages);
 	buf->pages = NULL;
 
 	/* add some codes for UNCACHED type here. TODO */