AMD PI agesawrapper: add PSPP (PCIe Speed Power Policy) interface

PSPP policy is defined in 3rdparty/blobs/pi/amd/*/AGESA.h
/// PCIe PSPP Power policy
typedef enum  {
  PsppDisabled,                                           ///< PSPP disabled
  PsppPerformance = 1,                                    ///< Performance
  PsppBalanceHigh,                                        ///< Balance-High
  PsppBalanceLow,                                         ///< Balance-Low
  PsppPowerSaving,                                        ///< Power Saving
  MaxPspp                                                 ///< Max Pspp for boundary check
} PCIE_PSPP_POLICY;

Change-Id: I7fe735cddea94a83e38d856a3de1f27735467a28
Signed-off-by: WANG Siyuan <wangsiyuanbuaa@gmail.com>
Signed-off-by: WANG Siyuan <SiYuan.Wang@amd.com>
Reviewed-on: http://review.coreboot.org/10461
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)

src/northbridge/amd/pi/agesawrapper.c

@@ -107,6 +107,7 @@ AGESA_STATUS agesawrapper_amdinitearly(void)
 	AmdEarlyParamsPtr = (AMD_EARLY_PARAMS *)AmdParamStruct.NewStructPtr;
 	OemCustomizeInitEarly (AmdEarlyParamsPtr);
 
+	AmdEarlyParamsPtr->GnbConfig.PsppPolicy = PsppDisabled;
 	status = AmdInitEarly ((AMD_EARLY_PARAMS *)AmdParamStruct.NewStructPtr);
 	if (status != AGESA_SUCCESS) agesawrapper_amdreadeventlog(AmdParamStruct.StdHeader.HeapStatus);
 	AmdReleaseStruct (&AmdParamStruct);