Linaro's Debian image for Dragonboard 410c is not upgradeable

“apt update” fails to update systemd on latest linaro “Debian image #1025”, see below error message from apt.
Is there a workaround? The “gpiod library” which is used for toggling gpios has dependencies on systemd. /sys/class/gpio and is the only way in new kernels to access gpio.
Without gpiod, DragonBoard 410c gpios can’t be accessed. Any ideas how else can we access the gpios? Please share.

This is the error from “apt update”:

Preparing to unpack …/systemd_255.2-4_arm64.deb …

  • The systemd package cannot be installed because this system does
  • not have a merged /usr.
  • Please install the usrmerge package to convert this system to merged-/usr.
  • For more information please read UsrMerge - Debian Wiki.