mb/google/dedede: Add dedede mainboard

Add mainboard stubs for Dedede. More functionalities will be added later.

BUG=b:144768001
TEST=Build test.

Change-Id: I7e6cb8adaee7b6bb95e9a96f96466646a78bd0fc
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38277
Reviewed-by: Aamir Bohra <aamir.bohra@intel.com>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/dedede/bootblock.c

@@ -0,0 +1,14 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2020 The coreboot project Authors.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include <bootblock_common.h>
+
+void bootblock_mainboard_init(void)
+{
+	/* TODO: Perform mainboard initialization */
+}