scsi: libsas: Delete SAS_SG_ERR

No LLDD sets exec status as SAS_SG_ERR, so remove support.

Link: https://lore.kernel.org/r/1645112566-115804-5-git-send-email-john.garry@huawei.com


Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>