net: hns3: do not reuse pfmemalloc pages

HNS3 driver allocates pages for DMA with dev_alloc_pages(), which
calls alloc_pages_node() with the __GFP_MEMALLOC flag. So, in case
of OOM condition, HNS3 can get pages with pfmemalloc flag set.

So do not reuse the pages with pfmemalloc flag set because those
pages are reserved for special cases, such as low memory case.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>