This patch adds proper detection support for more znver2 CPUs. Specifically, this adds in support for CPUs codenamed Renoir, Lucienne, and Mendocino. This was originally proposedfor Renoir in https://reviews.llvm.org/D96220 and got approved, but slipped through the cracks. However, there is still a demand for this feature. In addition to adding support for more znver2 CPUs, this patch also includes some additional refactoring and comments related to cpu model information for zen CPUs. Fixes https://github.com/llvm/llvm-project/issues/74934.