Migrate 206ax to SMM_MODULES

This gets rid of ugly tseg_relocate for bd82x6x.

This is backport of 29ffa54969 to bd82x6x.

Change-Id: I0f52540851ce8a7edaac257a2aa83d543bb5e530
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-on: http://review.coreboot.org/10351
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/northbridge/intel/sandybridge/sandybridge.h

@@ -99,6 +99,7 @@
 
 #define TOM		0xa0
 #define TOUUD		0xa8	/* Top of Upper Usable DRAM */
+#define BGSM		0xb4	/* Base GTT Stolen Memory */
 #define TSEG		0xb8	/* TSEG base */
 #define TOLUD		0xbc	/* Top of Low Used Memory */