[Backport to llvm_release_210] Update OCL nan builtin translation to work with bfloat type#3639

vmaksimo merged 2 commits intollvm_release_210KhronosGroup/SPIRV-LLVM-Translator:llvm_release_210from

backport/pr-3558-to-llvm_release_210KhronosGroup/SPIRV-LLVM-Translator:backport/pr-3558-to-llvm_release_210Copy head branch name to clipboard