Remove block_migration attribute from recover method

[Arun Mani]

During live migration failure of a VM, I noticed that the attributes passed in the recover method as part of migration rollback has block_migration attribute set.
This is actually removed from the _rollback_live_migration() method in the compute/manager.py module and hence the driver module needs to be updated accordingly.

In nova-powervm/virt/powervm/driver.py, the _migration_exception_util() calls the recover_method as below,
            recover_method(context, instance, dest, block_migration,
                           migrate_data)
The above code invokes _rollback_live_migration() method from nova/compute/manager.py and it has,
        _rollback_live_migration(self, context, instance,
                                 dest, migrate_data=None,
                                 migration_status='error')

This leads to a case, where the block_migration attribute gets substituted in place of migrate_data causing the migrate_data validations to fail during the migration rollback flow.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/465045

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/ocata
Review: https://review.openstack.org/465062

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/465045
Committed: https://git.openstack.org/cgit/openstack/nova-powervm/commit/?id=b07ea6602d71ccc34b8246ebdf4ab7c16d90aff4
Submitter: Jenkins
Branch: master

commit b07ea6602d71ccc34b8246ebdf4ab7c16d90aff4
Author: arunmani <email address hidden>
Date: Tue May 16 07:34:43 2017 -0400

    Remove block_migration attribute from migration rollback call

    In case of failed live migration of a VM, remove the block_migration
    attribute from being passed to _rollback_live_migration() method.
    This attribute isn’t required to be passed during the recover method
    invocation as part of migration failure.

    Change-Id: I5fb08612bab82ddbfd0f18634f2ee305c8ed80eb
    Closes-Bug: #1691079

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/465062
Committed: https://git.openstack.org/cgit/openstack/nova-powervm/commit/?id=a425c305dc68dfa81c8f963daa84720910aa7860
Submitter: Jenkins
Branch: stable/ocata

commit a425c305dc68dfa81c8f963daa84720910aa7860
Author: arunmani <email address hidden>
Date: Tue May 16 07:34:43 2017 -0400

    Remove block_migration attribute from migration rollback call

    In case of failed live migration of a VM, remove the block_migration
    attribute from being passed to _rollback_live_migration() method.
    This attribute isn’t required to be passed during the recover method
    invocation as part of migration failure.

    Change-Id: I5fb08612bab82ddbfd0f18634f2ee305c8ed80eb
    Closes-Bug: #1691079