net: hns3: fix mis-assignment to hdev->reset_level in hclge_reset

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

Since hclge_get_reset_level may return HNAE3_NONE_RESET,
so hdev->reset_level can not be assigned with the return
value in the hclge_reset(), otherwise, it will cause
the use of hdev->reset_level in hclge_reset_event get
into error.

Fixes: 012fcb52 ("net: hns3: activate reset timer when calling reset_event")

Feature or Bugfix:Bugfix

Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Reviewed-by: linyunsheng <linyunsheng@huawei.com>
Reviewed-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>