IO settings are useful for configuring ctl, phy odt, vref,
mr5, mode select and other needed input output operations
for lpddr4 or any other dramtype sdram.
Right now, this patch added IO setting for all supported
sdram frequencies.
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com> Signed-off-by: YouMin Chen <cym@rock-chips.com> Reviewed-by: Kever Yang <Kever.yang@rock-chips.com>