[llvm] [LoopCacheAnalysis] Fix loop cache cost to always round the cost up to the nearest integer number (PR #88915)

[Chen Zheng via llvm-commits]

https://github.com/chenzheng1030 commented:

Would you mind wait for some days for this patch? @RouzbehPaktinat 
Most changes happens inside PowerPC target. I will add some PowerPC reviewers and ping them for review. Thanks.

https://github.com/llvm/llvm-project/pull/88915