drm/ttm: max_cpages is in unit of native page

fix calculation.
Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_page_alloc.c

@@ -544,7 +544,7 @@ static int ttm_alloc_new_pages(struct list_head *pages, gfp_t gfp_flags,
 	int r = 0;
 	unsigned i, j, cpages;
 	unsigned npages = 1 << order;
-	unsigned max_cpages = min(count, (unsigned)NUM_PAGES_TO_ALLOC);
+	unsigned max_cpages = min(count << order, (unsigned)NUM_PAGES_TO_ALLOC);
 
 	/* allocate array for page caching change */
 	caching_array = kmalloc(max_cpages*sizeof(struct page *), GFP_KERNEL);