scsi: mac_esp: fix to pass correct device identity to free_irq()

free_irq() expects the same device identity that was passed to
corresponding request_irq(), otherwise the IRQ is not freed.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>