[llvm] [SPIRV] Add FPEncoding operand support for OpTypeFloat (PR #156871)

[Marcos Maronas via llvm-commits]

https://github.com/maarquitos14 approved this pull request.

LGTM. Should we add any test to see if we can properly generate bfloat16 type? 

https://github.com/llvm/llvm-project/pull/156871