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>

src/soc/intel/apollolake/include/soc/me.h

@@ -40,4 +40,18 @@ union me_hfsts1 {
 	} __packed fields;
 };
 
+/* ME Host Firmware Status Register 3 */
+union me_hfsts3 {
+	u32 data;
+	struct {
+		u32 reserved_0: 4;
+		u32 fw_sku: 3;
+		u32 reserved_7: 2;
+		u32 reserved_9: 2;
+		u32 resered_11: 3;
+		u32 resered_14: 16;
+		u32 reserved_30: 2;
+	} __packed fields;
+};
+
 #endif /* _APOLLOLAKE_ME_H_ */