sandybridge/raminit: Get max mem clock from devicetree

Note that the limit is not set in the devicetree.cb which use native
sandybridge raminit, as it is not needed. When that isn't set, it's
automatically set to zero, and when we find that, we automatically
return the default limit. Thus behavior isn't changed for any board.

Change-Id: I447399eea71355612b654710a56f3a0077c2f7f9
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/8476
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/northbridge/intel/sandybridge/chip.h b/src/northbridge/intel/sandybridge/chip.h
index 07809f5..a0abf44f 100644
--- a/src/northbridge/intel/sandybridge/chip.h
+++ b/src/northbridge/intel/sandybridge/chip.h
@@ -41,5 +41,11 @@
 	u32 gpu_cpu_backlight;	/* CPU Backlight PWM value */
 	u32 gpu_pch_backlight;	/* PCH Backlight PWM value */
 
+	/*
+	 * Maximum memory clock.
+	 * For example 666 for DDR3-1333, or 800 for DDR3-1600
+	 */
+	u16 max_mem_clock_mhz;
+
 	struct i915_gpu_controller_info gfx;
 };