rockchip: ram: add full feature rk3328 DRAM driver

This driver supports DDR3/LPDDR3/DDR4 SDRAM initialization.

Signed-off-by: YouMin Chen <cym@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
[cherry picked from commit https://github.com/rockchip-linux/u-boot/commit/9fb0777ec3cc6a89af9d2e0969c3bfe58306a88d

 with minor modifications]
Signed-off-by: Matwey V. Kornilov <matwey.kornilov@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>