rockchip/soc/drivers: Add DTPM description for rk3399

The DTPM framework does support now the hierarchy description.

The platform specific code can call the hierarchy creation function
with an array of struct dtpm_node pointing to their parent.

This patch provides a description of the big / Little CPUs and the
GPU and tie them together under a virtual 'package' name. Only rk3399 is
described now.

The description could be extended in the future with the memory
controller with devfreq.

The description is always a module and it describes the soft
dependencies. The userspace has to load the softdeps module in the
right order.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by; Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220128163537.212248-6-daniel.lezcano@linaro.org