[llvm] [AMDGPU] Swap select operands to allow later v_cndmask shrinking into vop2 (PR #142354)

[Ana Mihajlovic via llvm-commits]

mihajlovicana wrote:

One of the problems with this version is that this check is called for each select instructions, every time checking ALL select instructions. In the previous version the check was done only once when looking at compare instruction : https://github.com/llvm/llvm-project/pull/142140

https://github.com/llvm/llvm-project/pull/142354