rockchip: rk3399: Enable random generator on all boards

rockchip: rk3399: Enable random generator on all boards

The RK3399 SoC contain a crypto engine block that can generate random
numbers.

Imply DM_RNG and RNG_ROCKCHIP Kconfig options to take advantage of the
random generator on all RK3399 boards. Also remove the unnecessary use
of a status = "okay" prop.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>