scsi: libsas: Delete sas_ha_struct.lldd_module

Since libsas was introduced in commit 2908d778

 ("[SCSI] aic94xx: new
driver"), sas_ha_struct.lldd_module has only ever been set, so remove it.

Struct scsi_host_template already has a reference to the LLD driver
module as to stop the driver being removed unexpectedly.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20230815115156.343535-2-john.g.garry@oracle.com
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>