net: hns: set debug port irq index to 0

As debug ports are moved from service dsaf to debug dsaf,
the interrupts offset should start from 0, So this patch
re-defines the offset index of debug ports.

Signed-off-by: Daode Huang <huangdaode@hisilicon.com>
Signed-off-by: Yisen Zhuang <yisen.zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>