net/hns3: fix timing of clearing interrupt source

net/hns3: fix timing of clearing interrupt source

Currently, the PF/VF does not clear the interrupt source immediately
after receiving the interrupt. As a result, if the second interrupt
task is triggered when processing the first interrupt task, clearing
the interrupt source before exiting will clear the interrupt sources
of the two tasks at the same time. As a result, no interrupt is
triggered for the second task.

Clearing interrupt source immediately after checking event cause
ensures that:
1. Even if two interrupt tasks are triggered at the same time, they can
be processed.
2. If the second task is triggered during the processing of the first
task and the interrupt source is not cleared, the interrupt is reported
after vector0 is enabled.

Fixes: a5475d61fa34 ("net/hns3: support VF")
Fixes: 3988ab0eee52 ("net/hns3: add abnormal interrupt process")
Cc: stable@dpdk.org
Signed-off-by: Hongbo Zheng <zhenghongbo3@huawei.com>
Signed-off-by: Min Hu (Connor) <humin29@huawei.com>