RDMA/hns: Refactor code for readability

Put the code for checking the send doorbell status into a
separate function and call it from check_qp_db_process_status
to improve indenting and readability.

It fixes the warning from static checker:
drivers/infiniband/hw/hns/hns_roce_hw_v1.c:3562 check_qp_db_process_status()
warn: inconsistent indenting.

Fixes: 5f110ac4 ("IB/hns: Fix for checkpatch.pl comment style)
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Shaobo Xu <xushaobo2@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>