sb/intel/i82371eb: Add PIIX4 definitions

These new definitions will be used by two other changes.

Change-Id: I242244c444f36af188c871dce037a7a9250206cd
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38367
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/southbridge/intel/i82371eb/i82371eb.h b/src/southbridge/intel/i82371eb/i82371eb.h
index 2b53010..a566af776 100644
--- a/src/southbridge/intel/i82371eb/i82371eb.h
+++ b/src/southbridge/intel/i82371eb/i82371eb.h
@@ -40,6 +40,11 @@
 
 #define XBCS		0x4e	/* X-Bus chip select register */
 #define GENCFG		0xb0	/* General configuration register */
+#define   GPO2223	(1<<28) /* GPO22/23 */
+#define RTCCFG		0xcb	/* Real time clock configuration register */
+#define   RTC_POS_DECODE (1<<5)
+#define   UPPER_RAM_EN	(1<<2)
+#define   RTC_ENABLE	(1<<0)
 
 /* IDE */
 #define IDETIM_PRI	0x40	/* IDE timing register, primary channel */