cpu/intel/model_206ax: Add more CPU steppings

The Sandy Bridge steppings appear in the BWG, and Ivy Bridge steppings
appear in reference code. Add them for the sake of completeness.

Change-Id: I7d17cdd04a771ca319c908fc757f868e95ea7944
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48410
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/northbridge/intel/sandybridge/raminit_common.h

@@ -3,6 +3,7 @@
 #ifndef RAMINIT_COMMON_H
 #define RAMINIT_COMMON_H
 
+#include <cpu/intel/model_206ax/model_206ax.h>
 #include <stdint.h>
 
 #define BASEFREQ	133