This is a global variable used to track the state of the system, like booting, running, halting and so on.
This variable is based on the enum system_states enumeration.
For now, always set system_state to SYSTEM_RUNNING.
The amdgpu DRM driver started this in Linux 6.12.x.
This is part of the update of DRM drivers to Linux 6.12.81.
Sponsored by: The FreeBSD Foundation