scsi: hisi_sas: Drop hisi_sas_slot_abort()

For some time now we have not used hisi_sas_slot_abort() to handle erroring
slots, apart from in archaic v1 hw.

As such, remove this function and associated code. For v1 hw, move error
handling to same scheme as other hw revisions, where we allow erroring
commands to timeout.

Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>