Add u-boot,dm-spl and u-boot,dm-pre-reloc related properties for Rockchip RV1126 SoC. Both eMMC and SD boot are tested in Edgeble Neu2 SoM. Signed-off-by: Jagan Teki <jagan@edgeble.ai> Reviewed-by: Kever Yang <kever.yang@rock-chips.com>