soc/intel/dnv_ns: enable uCode PM Timer emulation

Denverton-NS supports uCode PM Timer emulation, according to Intel
doc#558579 rev2.2. Thus, enable it.

Change-Id: I21f55816da9f5e240fdf01a0e92b67b09ef38599
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57944
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/soc/intel/denverton_ns/Kconfig

@@ -15,6 +15,7 @@ config CPU_SPECIFIC_OPTIONS
 	def_bool y
 	select ARCH_X86
 	select BOOT_DEVICE_SUPPORTS_WRITES
+	select CPU_SUPPORTS_PM_TIMER_EMULATION
 	select DEBUG_GPIO
 	select SOC_INTEL_COMMON
 	select SOC_INTEL_COMMON_RESET

src/soc/intel/denverton_ns/cpu.c

@@ -94,6 +94,8 @@ static void denverton_core_init(struct device *cpu)
 	msr = rdmsr(IA32_MISC_ENABLE);
 	msr.lo |= SPEED_STEP_ENABLE_BIT;
 	wrmsr(IA32_MISC_ENABLE, msr);
+
+	enable_pm_timer_emulation();
 }
 
 static struct device_operations cpu_dev_ops = {