scsi: qla2xxx: Fix Management Server NPort handle reservation logic

After selecting the NPort handle/loop_id, set a bit in the loop_id_map to
prevent others from selecting the same NPort handle.

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>