x86/cpu: Add a X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS() macro

... to match Intel family 6 CPUs with steppings.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Mark Gross <mgross@linux.intel.com>
Link: https://lkml.kernel.org/r/20200506071516.25445-3-bp@alien8.de