Support delegation of bind_port to networking-odl backend driver.

Support delegation of bind_port to networking-odl backend driver.

The OpenDaylightMechanismDriver delegates bind_port to networking-odl
backend driver. Move check_segment toghether with bind_port as is
used only there. This will enabled extension of bind_port to
support other port types such as vhost-user in a separated patch-set
to networking-odl without requiring further changes to the front-end
component in neutron.

Change-Id: I27948ac0b440b8b4d04e496971593850e78739d0
Closes-Bug: #1477483
Depends-On: Id663147020b9780129c65ba0bb6d743a9de9cd4b