scsi: mpi3mr: Add support for queue command processing

scsi: mpi3mr: Add support for queue command processing

Send Port Enable Request to FW for Device Discovery.  As part of port
enable completion driver calls scan_start and scan_finished hooks.  SCSI
layer references like sdev, starget, etc. are added but actual device
discovery will be supported once driver adds complete event process
handling.

Link: https://lore.kernel.org/r/20210520152545.2710479-5-kashyap.desai@broadcom.com
Cc: sathya.prakash@broadcom.com
Cc: hare@suse.de
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>