[llvm] [LLVM][CodeGen] Remove +bf16 for ARM/AArch64 tests that don't strictly need the feature flag. (PR #204199)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> There's clang/test/CodeGen/AArch64/neon/bf16-getset.c left, otherwise LGTM. Thanks!

To keep the current PR llvm/test/codegen focused, I'll update the clang test(s) in a separate PR.

https://github.com/llvm/llvm-project/pull/204199