From Variscite Wiki
VAR-SOM-MX8X - Real Time Clock (RTC)

Setting the RTC

First set the system date & time:

# date --set="20171231 23:59"

Then set the HW RTC using the system date & time:

# hwclock --systohc --utc

Power down your board, wait 5 minutes and power up again, then check you system date & time and verify it is correct:

# date