drm/amdgpu: also track late init state

Successful sw_init() and hw_init() states are tracked, but not
late_init(). Various error paths may result in amdgpu_fini() being
called before .late init is done, so late_init needs to be tracked
to avoid unexpected or multiple .late_fini() calls.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>