[llvm] [SPIR-V] Fix OpDecorate emission after vreg def. (PR #114426)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

> > There are 2 broken tests, also broken on main:
> > 
> > * CodeGen/SPIRV/transcoding/RelationalOperators.ll
> > * CodeGen/SPIRV/uitofp-with-bool.ll
> >   Those are unrelated to this PR.
> 
> @Keenuts I'm checking this now.

Looks like this was fixed by https://github.com/llvm/llvm-project/pull/114630#event-15103865338

https://github.com/llvm/llvm-project/pull/114426