rockchip: ram: add full feature rk3328 dram driver

This driver supports ddr3/lpddr3/ddr4 sdram initialization.

Since we are going to merge the common part in dram driver for all
Rockchip SoCs, this patch become a RFC and can be used for people
who need it.

Change-Id: I255411e02089b461fdc384842e23ec2e092f87fb
Signed-off-by: YouMin Chen <[email protected]>
Signed-off-by: Kever Yang <[email protected]>

Author: keveryang