[clang] [Clang][AArch64] Expose compatible SVE intrinsics with only +sme (PR #95787)

[Paul Walker via cfe-commits]

https://github.com/paulwalker-arm commented:

Not for this patch but I do wonder if there's value in protecting non-bf16 instruction backed builtins (e.g. loadstone and shuffles) with the bf16 target guard.  I figure we'll either error on the use of the `svbfloat` type or the code generation should just work and thus there's be no reason to artificially restrict user code. 

https://github.com/llvm/llvm-project/pull/95787