[llvm] [LV] Also clamp MaxVF by trip count when maximizing vector bandwidth. (PR #149794)

[David Sherwood via llvm-commits]

david-arm wrote:

Perhaps good to wait for https://github.com/llvm/llvm-project/pull/149789 to land first, then rebase this PR to see what's changed?

https://github.com/llvm/llvm-project/pull/149794