I think that whether its racist or not depends on what happened between Moshiri and Lukaku.
If Moshiri made it all up and Ibra knew, then Ibra is being racist 100%. Whether he's winding up Lukaku about Voodoo itself or the news stories, he's using something that tends to be viewed as racial, maliciously.
If Moshiri got the wrong end of the stick because of something Lukaku said (it might have been an excuse to Moshiri), or if Lukaku did say it and then lied about it after, then Ibra is mocking Lukaku because of his own actions and so not racist.