src/intel: Define HFSTS3 register

Changes:
1. Define HFSTS3 register across SoCs(apl/cnl/icl/tgl).
2. Define cse_is_hfs3_fw_sku_custom() which checks ME's Firmware SKU
   is Custom or not.

TEST=Verified on hatch, soraka, bobba and iclrvp.

Change-Id: I4188e58a4a08d87be2d84674e00ed1407fb8bf82
Signed-off-by: Sridhar Siricilla <sridhar.siricilla@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38798
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Rizwan Qureshi <rizwan.qureshi@intel.com>
diff --git a/src/soc/intel/common/block/cse/cse.c b/src/soc/intel/common/block/cse/cse.c
index c82f3bd..39c30e9 100644
--- a/src/soc/intel/common/block/cse/cse.c
+++ b/src/soc/intel/common/block/cse/cse.c
@@ -270,6 +270,13 @@
 	return cse_check_hfs1_com(ME_HFS1_COM_SOFT_TEMP_DISABLE);
 }
 
+bool cse_is_hfs3_fw_sku_custom(void)
+{
+	union me_hfsts3 hfs3;
+	hfs3.data = me_read_config32(PCI_ME_HFSTS3);
+	return hfs3.fields.fw_sku == ME_HFS3_FW_SKU_CUSTOM;
+}
+
 /* Makes the host ready to communicate with CSE */
 void cse_set_host_ready(void)
 {