net: hns3: Fix an error macro definition of HNS3_TQP_STAT

The member "stats_offset" was designed to indicate the offset
of each member of struct ring_stats in struct hns3_enet_ring,
but forgot to add the offset of the member in struct ring_stats.

Fixes: 496d03e9 ("net: hns3: Add Ethtool support to HNS3 driver")
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>