nicira plugin: subnet loaded twice in add_router_interface

[Salvatore Orlando]

In add_router_interface: https://github.com/openstack/quantum/blob/master/quantum/plugins/nicira/QuantumPlugin.py#L1605
The subnet is loaded from the database at: https://github.com/openstack/quantum/blob/master/quantum/plugins/nicira/QuantumPlugin.py#L1635

and then again (if the router gateway is set) at: https://github.com/openstack/quantum/blob/master/quantum/plugins/nicira/QuantumPlugin.py#L1645

The second query can be avoided.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/32119

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/32119
Committed: http://github.com/openstack/quantum/commit/d671bada20e7f0a1a7bf587f40489a12551c717c
Submitter: Jenkins
Branch: master

commit d671bada20e7f0a1a7bf587f40489a12551c717c
Author: Salvatore Orlando <email address hidden>
Date: Fri Jun 7 12:33:44 2013 +0200

    nicira plugin: load subnet once when adding router interface

    Bug 1188562

    This patch ensure subnet is loaded only once from the database.
    Also, the port is now loaded from the database only if the
    corresponding NVP logical port is found.

    Change-Id: I1626c7b61ddc8e785d8ce2e39619da78b20ae61e