Mistake in usage drop_table in downgrade in migration

[Ann Taraday]

In method downgrade_cisco in migration folsom_initial instead of local method drop_tables op.drop_tables is used

File "/opt/stack/neutron/neutron/db/migration/alembic_migrations/versions/folsom_initial.py", line 468, in downgrade
    downgrade_cisco()
  File "/opt/stack/neutron/neutron/db/migration/alembic_migrations/versions/folsom_initial.py", line 541, in downgrade_cisco
    op.drop_tables(
AttributeError: 'module' object has no attribute 'drop_tables'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/53091

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/53091
Committed: http://github.com/openstack/neutron/commit/258aad077279b2020b47f4136747c1e5aa4bf5a8
Submitter: Jenkins
Branch: master

commit 258aad077279b2020b47f4136747c1e5aa4bf5a8
Author: Ann Kamyshnikova <email address hidden>
Date: Tue Oct 22 14:29:26 2013 +0400

    Fix downgrade in migration

    In method downgrade_cisco in migration folsom_initial instead of
    local method drop_tables op.drop_tables is used

    Closes-Bug: #1243148

    Change-Id: Ida6c52653c065e49c85141a7d1e61d394c1d709e