Remove cppc from the zen5 feature list

Motivations for taking `cppc` out:

* There's no upstream support in KVM for this AMD feature, so this won't
  be trivial to support for KVM-based virtualization. Plus AFAIK this
  feature isn't used in Linux yet.

* This does not seem to be something a compiler would use. For instance
  this is not included in GCC's znver5 list: https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html.

* There are other existing features that can tell zen5 apart from
  previous zen generations, for instance `avx_vnni` and `movdiri`, so
  the removal won't impact correct identification.

cpu/microarchitectures.json

@@ -2284,7 +2284,6 @@
         "clflushopt",
         "clwb",
         "clzero",
-        "cppc",
         "cx16",
         "f16c",
         "flush_l1d",