scsi: qla2xxx: Remove redundant wait when target is stopped.

Current code already destroy all target sessions when target Mode is
stopped. Target core would waits for all commands that belong to each
session to purge.  The extra wait for interrupts to settle down is not
relevant.

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