[llvm] [SPIRV] Fix SPV_KHR_expect_assume support (PR #67793)

[Ilia Diachkov via llvm-commits]

iliya-diyachkov wrote:

SPIRV translator do not generate OpAssumeTrueKHR and OpExpectKHR instructions without an error message. I think we should do the same.

https://github.com/llvm/llvm-project/pull/67793