net: hns3: change the time interval of int_gl calculating

Since we change the update rate of int_gl from every interrupt to every
one hundred interrupts, the old way to get time interval by int_gl value
is not accurate. This patch calculates the time interval using the jiffies
value.

Signed-off-by: Fuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>