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>
diff --git a/board/google/gru/MAINTAINERS b/board/google/gru/MAINTAINERS
new file mode 100644
index 0000000..e1cda75
--- /dev/null
+++ b/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