You mean like RDRAND? They exist, but if they're built into COTS platforms, you have to trust then, and if they're not, you have to do extra work to assure the joinery and handle failure modes.
To break the attack in this paper, you don't even need a hardware RNG; you just need hardware AES, like most modern platforms have (and like most mainstream operating systems use by default).
Suddenly after I read what you typed about RDRAND it clicked to me - you must never fully trust the hardware. Even if you TRUST the HW RNG, what is the harm of combining it into a broader RNG (assuming you know what you are doing).
To break the attack in this paper, you don't even need a hardware RNG; you just need hardware AES, like most modern platforms have (and like most mainstream operating systems use by default).