Support for GPUs on legacy nvidia drivers

[drobotk]

nvtop is mostly useless on older cards like fermi generation or lower which are stuck on drivers 390 or older.

The gpu usage on these old drivers can be retrieved by using nvidia-settings --query, provided there is an X server running.

$ nvidia-settings --query GPUUtilization

  Attribute 'GPUUtilization' (localhost:0[gpu:0]): graphics=0, memory=2, video=0, PCIe=0

Could this be implemented?

Thanks