staging: android: ion: Return void instead of int

Now, nobody care about the return value of ion_page_pool_add, therefore
we can just make it return void.
Acked-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion_page_pool.c

@@ -26,7 +26,7 @@ static void ion_page_pool_free_pages(struct ion_page_pool *pool,
 	__free_pages(page, pool->order);
 }
 
-static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
+static void ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
 {
 	mutex_lock(&pool->mutex);
 	if (PageHighMem(page)) {
@@ -37,7 +37,6 @@ static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
 		pool->low_count++;
 	}
 	mutex_unlock(&pool->mutex);
-	return 0;
 }
 
 static struct page *ion_page_pool_remove(struct ion_page_pool *pool, bool high)