scsi: scsi_debug: Drop scsi_debug_host_reset() device NULL pointer check

scsi: scsi_debug: Drop scsi_debug_host_reset() device NULL pointer check

The check for device pointer for the SCSI command is unnecessary, so drop
it.

The only caller is scsi_try_host_reset() -> eh_host_reset_handler(), and
there that pointer cannot be NULL.

Indeed, there is already code later in the same function which does not
check the device pointer for the SCSI command.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Link: https://lore.kernel.org/r/20230313093114.1498305-8-john.g.garry@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>