net: hns3: refine tx timeout count handle

In current codes, tx_timeout_cnt is used before increased,
then we can see the tx_timeout_count is still 0 from the
print when tx timeout happens, e.g.
"hns3 0000:7d:00.3 eth3: tx_timeout count: 0, queue id: 0, SW_NTU:
 0xa6, SW_NTC: 0xa4, HW_HEAD: 0xa4, HW_TAIL: 0xa6, INT: 0x1"

The tx_timeout_cnt should be updated before used.

Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>