Adding delay in OLT deletion

Change-Id: I461597855424c17d4635f10da82abe68a4d9009f
diff --git a/xos/synchronizer/steps/sync_olt_device.py b/xos/synchronizer/steps/sync_olt_device.py
index 81a9288..241e507 100644
--- a/xos/synchronizer/steps/sync_olt_device.py
+++ b/xos/synchronizer/steps/sync_olt_device.py
@@ -154,6 +154,12 @@
                 log.error("Failed to disable OLT device in VOLTHA: %s - %s" % (model.name, model.device_id), rest_response=request.text, rest_status_code=request.status_code)
                 raise Exception("Failed to disable OLT device in VOLTHA")
 
+            # NOTE [teo] wait some time after the disable to let VOLTHA doing its things
+            i = 0
+            for i in list(reversed(range(10))):
+                sleep(1)
+                log.info("Deleting the OLT in %s seconds" % i)
+
             # Delete the OLT device
             request = requests.delete("%s:%d/api/v1/devices/%s/delete" % (voltha['url'], voltha['port'], model.device_id))