rockchip: Add support for chromebook_bob

Bob is a 10-inch chromebook produced by Asus. It has two USB 3.0 type-C
ports, 4GB of SDRAM, WiFi and a 1280x800 display. It uses its USB ports
for both power and external display. It includes a Chrome OS EC
(Cortex-M3) to provide access to the keyboard and battery functions.

Support so far includes only:
- UART
- SDRAM
- MMC, SD card
- Cros EC (but not keyboard)

Not included:
- Keyboard
- Display
- Sound
- USB
- TPM

Bob is quite similar to Kevin, the Samsung Chromebook Plus, but support
for this is not provided in this series.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

board/google/gru/Kconfig

@@ -0,0 +1,15 @@
+if TARGET_CHROMEBOOK_BOB
+
+config SYS_BOARD
+	default "gru"
+
+config SYS_VENDOR
+	default "google"
+
+config SYS_CONFIG_NAME
+	default "gru"
+
+config BOARD_SPECIFIC_OPTIONS # dummy
+	def_bool y
+
+endif

board/google/gru/MAINTAINERS

@@ -0,0 +1,6 @@
+CHROMEBOOK BOB BOARD
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+F:	board/google/gru/
+F:	include/configs/gru.h
+F:	configs/chromebook_bob_defconfig

board/google/gru/Makefile

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright 2019 Google LLC
+
+obj-y += gru.o

board/google/gru/gru.c

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 Google
+ */
+
+#include <common.h>
+
+int board_init(void)
+{
+	return 0;
+}
+
+/* provided to defeat compiler optimisation in board_init_f() */
+void gru_dummy_function(int i)
+{
+}