uboot-phytec

rockchip: rk3399: add target type for evb based board

There are many boards share the board file and device header file with
rk3399 evb, add target type MACRO so that it is fixed instead of default
to the first target in "RK3399 board select".

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>