That was the way it was first reported but then the name “Rolls Royce” was removed entirely from the story, which is strange, but it is indicative that Rolls Royce is a Boeing subcontractor that makes those engines to Boeing specs and thus for all intents and purposes and legal reasons they are Boeing engines.
No the engine reporting data system was almost certainly part of the Rolls Royce warranty (the engines may even have been leased). That's why the Malaysians could opt out of the ACARS stuff, but needed the engine reporting to Rolls.
Rolls would probably be offended to call hem Boeing engines. From wiki - “Versions of the Trent are in service on the Airbus A330, A340, A380, Boeing 777, and 787, and variants are in development for the forthcoming A350 XWB.”
The Malaysian Airlines 777’s definitely used RR engines
http://www.malaysiaairlines.com/my/en/mh-experience/our-fleet/boeing-777-200.html