No. This idea comes from the claims that Hitler was trying to create a "master race". In fact, he never used the term "master race", and if this was his ideology, there would have been mention of it in his book, Mein Kampf. But like the claims of how his plans to exterminate the Jews were said to have been in the book, neither one appears anywhere.
Hitler was antisemitic. But surprise! So were many other people in countries all over the world. This doesn't prove white supremacy. Like the true reason Germany lost WW1, the Jews ("Zionists", actually - people don't understand the difference) actually did something to make the hate happen. It has nothing to do with "race" or "culture" - it has to do with an event that damaged an entire country.
As for the Gypsies, homosexuals and other non-Jews on the list of people that Hitler hated, these groups are disliked by a lot of people for various reasons that don't include white supremacy.
But when you have someone who was falsely accused of exterminating Jews when this theme park opened 18 years before Hitler even became Chancellor, making him a convenient target for other accusations - all based on hate propaganda, making him a white supremacist makes as much sense as anything.