[llvm] [LoopInterchange] Avoid using CacheCost if cache line size is zero (PR #126021)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

I also found that the cache line size is not defined for the Neoverse family, so the default value of zero is used.

https://github.com/llvm/llvm-project/pull/126021