pillar: device-steps.sh: Load time from RTC at boot

[rene]

Set system time from RTC (when available) at boot so we can get the correct date earlier without need to wait for the chrony daemon initialization, this is specially important for ARM devices that don't have a battery packed RTC, in the first boot the date will be invalid, but it doesn't get lost between restarts (while the RTC is powered).

cc: @rouming