[llvm] [SPIR-V] Add SPV_INTEL_2d_block_io extension (PR #140140)

[Michal Paszkowski via llvm-commits]

michalpaszkowski wrote:

@YuriPlyakhin Thank you for working on this! LGTM! Let's wait for the GitHub Actions Workflows to pass and I can merge the change if that's okay with you.

https://github.com/llvm/llvm-project/pull/140140