fix warning in arch/x86/kernel/cpu/intel_cacheinfo.c

fix this warning:

  arch/x86/kernel/cpu/intel_cacheinfo.c:139: warning: ‘k8_nb_id’ defined but not used
  arch/x86/kernel/cpu/intel_cacheinfo.c:527: warning: ‘free_cache_attributes’ defined but not used
  arch/x86/kernel/cpu/intel_cacheinfo.c:538: warning: ‘detect_cache_attributes’ defined but not used

Unused variables in the !CONFIG_SYSCTL case.

Signed-off-by: Ingo Molnar <mingo@elte.hu>