amd/bettong: Enable fan control

1. Use enable_imc_thermal_zone to enable fan control.
2. The ACPI method ITZE works on Ubuntu 14.04 and Windows 7
but does not work on Windows 8, so I didn't use it.
After this issue is fixed, I'll add ACPI_ENABLE_THERMAL_ZONE
in bettong/Kconfig.
3. Fan control works on Bettong. I used "APU Validation Toolkit"
to test on Windows 8. This tool can put load to APU. The fan's
behaviour is just like bettong/fchec.c defined. When the temperature
is 40 Celsius, the fan start to run.

Change-Id: I0fc22974a7a7cf3f6bdf5f1c66be95219a177e12
Signed-off-by: WANG Siyuan <wangsiyuanbuaa@gmail.com>
Signed-off-by: WANG Siyuan <SiYuan.Wang@amd.com>
Reviewed-on: http://review.coreboot.org/10721
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marc.jones@se-eng.com>

src/mainboard/amd/bettong/BiosCallOuts.c

@@ -76,6 +76,9 @@ AGESA_STATUS Fch_Oem_config(UINT32 Func, UINT32 FchData, VOID *ConfigPtr)
 	} else if (StdHeader->Func == AMD_INIT_ENV) {
 		FCH_DATA_BLOCK *FchParams_env = (FCH_DATA_BLOCK *)FchData;
 		printk(BIOS_DEBUG, "Fch OEM config in INIT ENV ");
+#if IS_ENABLED(CONFIG_HUDSON_IMC_FWM)
+		oem_fan_control(FchParams_env);
+#endif
 
 		/* XHCI configuration */
 #if CONFIG_HUDSON_XHCI_ENABLE