x86/cpuidle: add Westmere-EX support to hw residencies reading logic

This is in accordance with
http://software.intel.com/en-us/articles/intel-processor-identification-with-cpuid-model-and-family-numbers/

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/acpi/cpu_idle.c
+++ b/xen/arch/x86/acpi/cpu_idle.c
@@ -120,6 +120,7 @@ static void do_get_hw_residencies(void *
     /* Westmere */
     case 0x25:
     case 0x2C:
+    case 0x2F:
         GET_PC3_RES(hw_res->pc3);
         GET_PC6_RES(hw_res->pc6);
         GET_PC7_RES(hw_res->pc7);