[llvm] [AMDGPU] Swap V_CNDMASK operands to shrink it into VOP2 (PR #135162)

[Ana Mihajlovic via llvm-commits]

mihajlovicana wrote:

> * Needs rebase
> * Please add tests for a negative case, case with source modifiers and when shouldSwapCndOperands counter is positive.

should this be added for all compare kinds?

https://github.com/llvm/llvm-project/pull/135162