scsi: qla2xxx: Replace usage of spin_lock with spin_lock_irqsave

Convert usage of spin_lock to spin_lock_irqsave because qla2xxx driver
can access all the data structures in an interrupt context.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>