nb/intel/sandybridge: use MESEG register names from datasheet

I used register names guessed on what the registers do, since the SNB
documentation marked those registers as reserved; the IVB documentation
(326765-005) has names for the registers, so I'll use those.

Change-Id: I2f1194438a56546d9836dd12635d064a900a2fd8
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38008
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/sandybridge/sandybridge.h b/src/northbridge/intel/sandybridge/sandybridge.h
index 6bfe88b..6a9c00f 100644
--- a/src/northbridge/intel/sandybridge/sandybridge.h
+++ b/src/northbridge/intel/sandybridge/sandybridge.h
@@ -82,8 +82,8 @@
 #define PAVPC		0x58	/* Protected Audio Video Path Control */
 #define DPR		0x5c	/* DMA Protected Range */
 
-#define MEBASE		0x70
-#define MEMASK		0x78
+#define MESEG_BASE	0x70
+#define MESEG_MASK	0x78
 
 #define PAM0		0x80
 #define PAM1		0x81