x86/intel_idle: add Gemini Lake support

Gemini Lake uses the same C-states as Broxton and also uses the
IRTL MSR's to determine maximum C-state latency.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Acked-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/idle/intel_idle.c

@@ -1097,6 +1097,7 @@ static const struct x86_cpu_id intel_idle_ids[] __initconst = {
 	ICPU(INTEL_FAM6_XEON_PHI_KNL,		idle_cpu_knl),
 	ICPU(INTEL_FAM6_XEON_PHI_KNM,		idle_cpu_knl),
 	ICPU(INTEL_FAM6_ATOM_GOLDMONT,		idle_cpu_bxt),
+	ICPU(INTEL_FAM6_ATOM_GEMINI_LAKE,	idle_cpu_bxt),
 	ICPU(INTEL_FAM6_ATOM_DENVERTON,		idle_cpu_dnv),
 	{}
 };
@@ -1309,6 +1310,7 @@ static void intel_idle_state_table_update(void)
 		ivt_idle_state_table_update();
 		break;
 	case INTEL_FAM6_ATOM_GOLDMONT:
+	case INTEL_FAM6_ATOM_GEMINI_LAKE:
 		bxt_idle_state_table_update();
 		break;
 	case INTEL_FAM6_SKYLAKE_DESKTOP: