[llvm] [AArch64] Update feature dep. for Armv9.6 extensions (PR #125874)

[via llvm-commits]

llvmbot wrote:

<!--IGNORE-->
>/cherry-pick [cc0d4a5](https://github.com/llvm/llvm-project/commit/cc0d4a5188f9e41dd8e00048d17b87529e28b694)

Error: Command failed due to missing milestone.

https://github.com/llvm/llvm-project/pull/125874