smi: make tseg_relocate check pointer offset

In case tseg_relocate() is called again on a pointer we should not
relocate it again.

Change-Id: Ida1f9c20dc94b448c773b14d8864afe585369119
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/1740
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/southbridge/intel/bd82x6x/smihandler.c

@@ -65,7 +65,7 @@ u32 smi_get_tseg_base(void)
 void tseg_relocate(void **ptr)
 {
 	/* Adjust pointer with TSEG base */
-	if (*ptr)
+	if (*ptr && *ptr < (void*)smi_get_tseg_base())
 		*ptr = (void *)(((u8*)*ptr) + smi_get_tseg_base());
 }
 #endif