scsi: mpt3sas: Add support for shared host tagset for CPU hotplug

scsi: mpt3sas: Add support for shared host tagset for CPU hotplug

MPT Fusion adapters can steer completions to individual queues and we now
have support for shared host-wide tags in the I/O stack. The addition of
the host-wide tags allows us to enable multiqueue support for MPT Fusion
adapters. Once host-wise tags are enabled, the CPU hotplug feature is also
supported.

Allow use of host-wide tags to be disabled through the "host_tagset_enable"
module parameter. Once we do not have any major performance regressions
using host-wide tags, we will drop the hand-crafted interrupt affinity
settings.

Performance is meeting expectations. About 3.1M IOPS using 24 Drive SSD on
Aero controllers.

Link: https://lore.kernel.org/r/20210202095832.23072-1-sreekanth.reddy@broadcom.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>