board: rockchip: Add Bananapi R2Pro Board

Add Bananapi R2 Pro board.

tested:
- sdcard
- both front usb-ports
- sata
- wan-port

lan-ports are connected to mt7531 switch where driver needs to be
separated from mtk ethernet-driver.

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Jonas Karlman <jonas@kwiboo.se>
diff --git a/doc/board/rockchip/rockchip.rst b/doc/board/rockchip/rockchip.rst
index 4ca59fd..8262fc0 100644
--- a/doc/board/rockchip/rockchip.rst
+++ b/doc/board/rockchip/rockchip.rst
@@ -102,6 +102,7 @@
 
 * rk3568
      - Rockchip Evb-RK3568 (evb-rk3568)
+     - Banana Pi BPI-R2 Pro (bpi-r2-pro-rk3568)
      - EmbedFire LubanCat 2 (lubancat-2-rk3568)
      - FriendlyElec NanoPi R5C (nanopi-r5c-rk3568)
      - FriendlyElec NanoPi R5S (nanopi-r5s-rk3568)