[llvm] [LV][NFC] Add option to control debug printing of cost per lane (PR #201824)

[David Sherwood via llvm-commits]

david-arm wrote:

If it's ok, I think I'll go with @sdesmalen-arm's suggestion and use APFloat. I'll also want to update this PR to fix another file - see https://github.com/llvm/llvm-project/pull/202291

https://github.com/llvm/llvm-project/pull/201824