[mlir] [clang] [clang-tools-extra] [llvm] [mlir][spirv] Fix spirv dialect to support Specialization constants as GlobalVar initializer (PR #75660)

[Lei Zhang via llvm-commits]

antiagainst wrote:

Thanks for the contribution! Sorry about the delay in reviews. I do have some style-ish comments but given this has been a while I just went ahead fixed them and will land this path directly. Thanks again! 

https://github.com/llvm/llvm-project/pull/75660