The previously stated speed of sdr-104 in is too high for the hardware
to reliably communicate with some fast SD cards.
Rockchip boards have a common bug when operating uhs speed, which will
hang the system during a soft reboot.
To be on the safe side, lower the speed to workaround.
Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>
b0e869501a