net: hns3: Fix an error of total drop packet statistics

The dropped tx/rx packets number of each tqp should also
be counted into the total drop tx/rx packets numbers.

Fixes: 76ad4f0e ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
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>