scsi: scsi_debug: Drop scsi_debug_abort() NULL pointer checks

scsi: scsi_debug: Drop scsi_debug_abort() NULL pointer checks

The SCSI cmnd pointer arg would never be NULL, so drop the check. In
addition, its SCSI device pointer would never be NULL.

The only caller is scsi_send_eh_cmnd() -> scsi_abort_eh_cmnd() ->
scsi_try_to_abort_cmd() -> scsi_try_to_abort_cmd(), and in the origin of
that chain those pointers cannot be NULL.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Link: https://lore.kernel.org/r/20230313093114.1498305-4-john.g.garry@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>