Port legacy kernel Rockchip Hardware Random Number Generator forward into Edge

Lack of a HW RNG for Rockchip was causing a 15 second hang early in userspace initialization.

This patch adds the rockchip-rng driver to the rockchip64 kernel.

However, initially, only the rk3308.dtsi enables it. Support could be added later to other rk*.dtsi files.

The RNG driver fills the entropy pool quickly, early in boot, so there’s no longer a need to wait for it.