RDMA/hns: Fix the chip hanging caused by sending doorbell during reset

On hi08 chip, There is a possibility of chip hanging when sending doorbell
during reset. We can fix it by prohibiting doorbell during reset.

Fixes: 2d407888

 ("RDMA/hns: Add support for processing send wr and receive wr")
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>