rockchip: px30: move secure init to separate file

Similar to others like rk3399 and rk3288 move the secure init to a
separate file to unclutter the soc init a bit.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Change-Id: Iebb38e24f1c7fe5353f139c896fb8ca769bf9691
6 files changed