scsi: scsi_debug: remove jiffies_to_timespec

There is no need to go through an intermediate timespec to convert to
ktime_t when we just want a simple multiplication. This gets rid of one
of the few users of jiffies_to_timespec, which I hope to remove as part
of the y2038 cleanup.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>