Remove _remove_router_interface_with_port_id()

_remove_router_interface_with_port_id() is just a wrapper method
which calls remove_router_interface() with an assertion.
The assertion seems unnecessary because it is called on the cleanup
and we don't do such check on the other places.
This patch just replaces the redunadnt method with direct call.

Change-Id: I82fd96be1f27dc9f9e58b5eeaa562ef3404f3382
2 files changed