soc/intel/skylake: Add device settings for PL4 power limit

PL4 is a preemptive CPU package peak power limit,it will never be exceeded.
Power is preemptively lowered before limit is reached.

This change provides option in devicetree and feeds FSP PowerLimit4 UPD for
power limit purpose.

Signed-off-by: Praveen hodagatta pranesh <praveenx.hodagatta.pranesh@intel.com>
Change-Id: I64b5a029104a102e5741e8b37c7992f2693180e8
Reviewed-on: https://review.coreboot.org/c/29808
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/intel/skylake/chip_fsp20.c

@@ -369,6 +369,7 @@ void platform_fsp_silicon_init_params_cb(FSPS_UPD *supd)
 
 	tconfig->PchLockDownGlobalSmi = config->LockDownConfigGlobalSmi;
 	tconfig->PchLockDownRtcLock = config->LockDownConfigRtcLock;
+	tconfig->PowerLimit4 = config->PowerLimit4;
 	/*
 	 * To disable HECI, the Psf needs to be left unlocked
 	 * by FSP till end of post sequence. Based on the devicetree