[llvm] [mlir] [SPIRV] Support for the extension SPV_ALTERA_blocking_pipes (PR #138675)

[Dmitry Sidorov via llvm-commits]

MrSidims wrote:

@aadeshps-mcw thanks! If you don't mind, I've changed the name of the PR as well as the description, as these 2 are used for a squashed commit.

https://github.com/llvm/llvm-project/pull/138675