mainboard/google/reef: Bump mainboard mem version

This change is to bump fsp_memory_mainboard_version in order to
trigger MRC full training

BUG=b:119481870
CQ-DEPEND=CL:*716558
BRANCH=reef, coral
TEST=make sure MRC retraining is triggered and the MRC cache is
     updated to newer version.

Change-Id: I92463045f7a808fb25aaa7a2d5f6fcde36dfb458
Signed-off-by: Kane Chen <kane.chen@intel.com>
Reviewed-on: https://review.coreboot.org/c/29647
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/reef/variants/baseboard/memory.c

@@ -17,6 +17,7 @@
 #include <gpio.h>
 #include <soc/meminit.h>
 #include <variant/gpio.h>
+#include <fsp/api.h>
 
 const struct lpddr4_swizzle_cfg baseboard_lpddr4_swizzle = {
 	/* CH0_DQA[0:31] SoC pins -> U22 LPDDR4 module pins */
@@ -167,3 +168,8 @@ size_t __weak variant_memory_sku(void)
 	 * exist. */
 	return gpio_pullup_base2_value(pads, ARRAY_SIZE(pads));
 }
+
+uint8_t fsp_memory_mainboard_version(void)
+{
+	return 1;
+}