ram: rockchip: Compute ddr capacity based on grf split

DDR chip capacity is computed based on GRF split in some
Rockchip SoC's like PX30 and RV1126.

Add split argument in ddr print info so-that the respective
ddr driver will pass the grf split.

Signed-off-by: YouMin Chen <cym@rock-chips.com>
Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>