dma-buf: cma_heap: Fix memory leak in CMA heap

REFERENCE:
https://git.seco.com/edgehog/bsp/rockchip/linux-seco-rk/-/commit/1935d6e94bc94e18c224eafb97d30e66f7ce31c6

drivers/dma-buf/heaps/cma_heap.c

@@ -245,6 +245,9 @@ static void cma_heap_dma_buf_release(struct dma_buf *dmabuf)
 		vunmap(buffer->vaddr);
 	}
 
+	/* free page list */
+	kfree(buffer->pages);
+	/* release memory */
 	cma_release(cma_heap->cma, buffer->cma_pages, buffer->pagecount);
 	kfree(buffer);
 }