The steppings correspond to the CPUID bits 3:0, so move them to the CPU
scope, and include the CPU header from files using the stepping macros.
Change-Id: Idf8fba4911f98953bb909777aea57295774d8400
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48409
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>