dt-bindings: arm: rockchip: add Banana Pi P2 Pro board

dt-bindings: arm: rockchip: add Banana Pi P2 Pro board

BBanana Pi P2 Pro is the SBC made by Shenzhen SINOVOIP based on
Rockchip RK3308.

Banana Pi P2 Pro features:
- Rockchip RK3308B-S
- DDR3 512 MB
- eMMC 8 GB
- 100M lan + onboard PoE
- 40 pin and 12 pin headers
- AP6256 BT + WIFI
- TF card slot
- 2x USB 2.0 (Type-C OTG and Type-A)
- Headphone jack

Add devicetree binding for Banana Pi P2 Pro.

Signed-off-by: Dmitry Yashin <[email protected]>
Acked-by: Krzysztof Kozlowski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Heiko Stuebner <[email protected]>