ofproto: Delete all groups and meters when (un)configuring a controller.
Open vSwitch has always deleted all flows from the flow table whenever a
controller is configured or whenever all the controllers are unconfigured.
After this commit, OVS additionally deletes all OpenFlow groups and meters.
Suggested-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com> Suggested-by: Jan Scheurich <jan.scheurich@ericsson.com> Signed-off-by: Ben Pfaff <blp@ovn.org> Acked-by: Jan Scheurich <jan.scheurich@ericsson.com> Tested-by: Jan Scheurich <jan.scheurich@ericsson.com> Reviewed-by: Greg Rose <gvrose8192@gmail.com> Tested-by: Greg Rose <gvrose8192@gmail.com>