core: Basic cleanup in InterfaceDaoDbFacadeImpl

Removed a warning suppression that was no longer required, and changed
a variable name from "stats" to "entity" where it was more fitting.

Change-Id: Id08a742d431232097a6c2a9556b3aab6c872d336
Signed-off-by: Lior Vernia <lvernia@redhat.com>