Select the DM_REGULATOR_FIXED on RK3568 platform. Co-developed-by: Suniel Mahesh <sunil@amarulasolutions.com> Signed-off-by: Suniel Mahesh <sunil@amarulasolutions.com> Signed-off-by: Manoj Sai <abbaraju.manojsai@amarulasolutions.com> Reviewed-by: Kever Yang <kever.yang@rock-chips.com>