scsi: libsas: remove unused variable sas_ha

Remove unused variable sas_ha to clean up build warning
"unused variable  sas_ha  [-Wunused-variable]"

Fixes: 042ebd29 ("scsi: libsas: kill useless ha_event and do some cleanup")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>