x86: intel_cacheinfo: fix compiler warning

fix the following warning:

  CC      arch/x86/kernel/cpu/intel_cacheinfo.o
  arch/x86/kernel/cpu/intel_cacheinfo.c:314: warning: 'cpuid4_cache_lookup' defined but not used

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>