scsi: st: ERASE does not change tape location

The SCSI ERASE command erases from the current position onwards.  Don't
clear the position variables.

Signed-off-by: Kai Mäkisara <Kai.Makisara@kolumbus.fi>
Link: https://lore.kernel.org/r/20250311112516.5548-3-Kai.Makisara@kolumbus.fi


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>