mb/google/hatch/var/kindred: Implement variant_devtree_update()

This change provides an implementation of variant_devtree_update() for
kindred that disable eMMC controller when SKU ID = 1 or 3

BUG=b:132918661
TEST=Verify eMMC is disabled when SKU ID = 1 or 3

Change-Id: I8ccb4dae54f223881e0ced9e034bf45b994cc6f2
Signed-off-by: David Wu <david_wu@quanta.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34400
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

src/mainboard/google/hatch/variants/kindred/Makefile.inc

@@ -21,3 +21,4 @@ SPD_SOURCES += 16G_2666   # 0b101
 
 bootblock-y += gpio.c
 ramstage-y += gpio.c
+ramstage-y += variant.c

src/mainboard/google/hatch/variants/kindred/variant.c

@@ -0,0 +1,34 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2019 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <baseboard/variants.h>
+#include <soc/pci_devs.h>
+#include <ec/google/chromeec/ec.h>
+
+void variant_devtree_update(void)
+{
+	uint32_t sku_id;
+	struct device *emmc_host;
+
+	emmc_host = pcidev_path_on_root(PCH_DEVFN_EMMC);
+
+	if (emmc_host == NULL)
+		return;
+
+	/* SKU ID 1, 3 doesn't have a eMMC device, hence disable it. */
+	sku_id = get_board_sku();
+	if (sku_id == 1 || sku_id == 3)
+		emmc_host->enabled = 0;
+}