net: hns3: add counter for times RX pages gets allocated

Currently, using "ethtool --statistics" can show how many time RX
page have been reused, but there is no counter for RX page not
being reused.

This patch adds non_reuse_pg counter to better debug the performance
issue, because it is hard to determine when the RX page is reused
or not if there is no such counter.

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>