[clang] [Clang][AArch64] Add fp8 variants for untyped NEON intrinsics (PR #128019)

[via cfe-commits]

Lukacma wrote:

> For my education can you explain why the fp8 variants are broken out into their own definitions. Taking VREV64_MF8 as an example, it looks like you should be able to add the new type strings to the current definition?

That's a good question. Its been a while since I implemented this patch, so I have forgotten my reasoning behind this, but I think this might be because I was originally not sure if we want to target guard these, behind fp8 feature flag. Since it looks like we are not doing that I can merge them back to their original intrinsics

https://github.com/llvm/llvm-project/pull/128019