Revert "Disable f16 on AArch64 without the neon feature"

The LLVM issue [1] was resolved and the fix was synced to rust-lang/rust
in [2].

This reverts commit 5cf417a.

[1]: llvm/llvm-project#129394
[2]: rust-lang/rust#138695

Author: tgross35

compiler-builtins/configure.rs

@@ -91,8 +91,6 @@ pub fn configure_f16_f128(target: &Target) {
     let f16_enabled = match target.arch.as_str() {
         // Unsupported <https://github.com/llvm/llvm-project/issues/94434>
         "arm64ec" => false,
-        // Crash in LLVM20 <https://github.com/llvm/llvm-project/issues/129394>
-        "aarch64" if !target.features.iter().any(|f| f == "neon") => false,
         // Selection failure <https://github.com/llvm/llvm-project/issues/50374>
         "s390x" => false,
         // Infinite recursion <https://github.com/llvm/llvm-project/issues/97981>