[llvm] [clang] Remove experimental from Vector Crypto extensions (PR #69000)

[Eric Biggers via cfe-commits]

ebiggers wrote:

Hi!  What's the status of this pull request?  Are there any major issues remaining?  It would be very useful to have the LLVM assembler officially support the vector crypto extensions.  I've been reviewing the [RISC-V vector crypto accelerated crypto routines for the Linux kernel](https://lore.kernel.org/linux-crypto/20231025183644.8735-1-jerry.shih@sifive.com), and currently they're emitting the instructions as bare `.inst`s in order to not rely on the assembler, which is quite ugly.  The GNU assembler already released the support for this a few months ago, in v2.41.

FYI @JerryShih and @phoebesv

https://github.com/llvm/llvm-project/pull/69000