Updating ASN in the Global system config

provison_control does two jobs,
1. Updates the ASN in the clobal sustem config
2. adds the control node as bgp router
So need to execute provision_control.py with required argument twice in
prov_control_bgp task.

Change-Id: Icfb0aec958015a72baf423c54fa337121ac336ba
Closes-Bug: 1391177
Merge "Updating ASN in the Global system config"