ram: rk3399: Update lpddr4 vref_mode_ac

Update vref_mode_ac for lpddr4 based on VDDQ/3/2=16.8%

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>
1 file changed