rockchip: rk322x: set the DDR region as non-secure in SPL

Disable the ddr secure region setting in SPL and the ddr memory
becomes non-secure, every one can access it. the trust firmware
like OPTEE should have the correct setting for it after SPL if
there is one.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>