As a performance enhancement, make the completion queue interrupts managed.

In addition, in commit bf0beec0 ("blk-mq: drain I/O when all CPUs in a
hctx are offline"), CPU hotplug for MQ devices using managed interrupts is
made safe. So expose HW queues to blk-mq to take advantage of this.

Flag Scsi_host.host_tagset is also set to ensure that the HBA is not sent
more commands than it can handle. However the driver still does not use
request tag for IPTT as there are many HW bugs means that special rules
apply for IPTT allocation.

Link: https://lore.kernel.org/r/1606905417-183214-6-git-send-email-john.garry@huawei.comSigned-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>