BUG-1287: migrate pcep-tunnel-provider

Data store has a new set of APIs, which are more efficient. This is a
straightforward migration, without taking advantage of the full APIs
available.

Change-Id: I19e7d49f69ecc0bf24fbb511e7bb05df682d5c73
Signed-off-by: Robert Varga <rovarga@cisco.com>
Signed-off-by: Milos Fabian <milfabia@cisco.com>