scsi: pm8001: Rework shost initial values

scsi: pm8001: Rework shost initial values

Some values in pm8001_prep_sas_ha_init() are set the same as they would be
set in scsi_host_alloc(), or could be in the sht (which would be better),
or later just overwritten, so rework the following:

 - cmd_per_lun can be set in the sht

 - max_lun and max_channel are as scsi_host_alloc() (so no need to set)

 - can_queue is later overwritten (so don't set in
   pm8001_prep_sas_ha_init())

Link: https://lore.kernel.org/r/1654879602-33497-2-git-send-email-john.garry@huawei.com
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>