[llvm] [MathExtras] Fix typos in hex fp constant values. NFC. (PR #123047)

[Jay Foad via llvm-commits]

jayfoad wrote:

I also double checked against the OEIS references that the decimal values were the correct ones (but only for the ones where the decimal and hex didn't agree).

https://github.com/llvm/llvm-project/pull/123047