uboot-phytec

ram: rockchip: add phy driver code for PX30

This sdram_phy_px30.c is based on PX30 SoC, the functions are common
for phy, other SoCs with similar hardware could re-use it.

Signed-off-by: YouMin Chen <cym@rock-chips.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>