scsi: libsas: Delete struct scsi_core

scsi: libsas: Delete struct scsi_core

Since commit 79855d178557 ("libsas: remove task_collector mode"), struct
scsi_core only contains a reference to the shost. struct scsi_core is only
used in sas_ha_struct.core, so delete scsi_core and replace with a
reference to the shost there.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20230815115156.343535-5-john.g.garry@oracle.com
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>