qcacmn: move vdev_id_map[vdev_id] null setting after dp_rx_vdev_detach

In dp_vdev_detach_wifi3(), the vdev_id_map[vdev_id] set to
null is happened before dp_rx_vdev_detach(). but the call back
done by dp_rx_vdev_detach still need to get the vdev pointer by
vdev_id, it will return NULL by current logic.

Move vdev_id_map[vdev_id] null setting after dp_rx_vdev_detach().

Change-Id: Ibaf506cfef83d68a21033e67395c37f53aeb4489
CRs-Fixed: 2681712