That message is a warning and not a critical issue - it can be ignored - this error usually comes from the smu7_apply_state_adjust_rules() which are defined in 'drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c'
You might want to check for upgraded AMD drivers or it could be a minor kernel driver issue either way no worries also check to see if you are using the latest kernel from Ubuntu the HWE version
