arm64: dts: rockchip: split rk3399-rockpro64 for v2 and v2.1 boards

This patch splits rk3399-rockpro64 dts file to 2 files for v2 and
v2.1 boards.

Both v2 and v2.1 boards can use almost same settings but we find a
difference in I2C address of audio CODEC ES8136.

Reported-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Link: https://lore.kernel.org/r/20191202055929.26540-1-katsuhiro@katsuster.net
[put pine64,rockpro64-v2.* into an enum]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>