drm/amdgpu: stop touching sched.ready in the backend

[ Upstream commit a2b4785f01280a4291edb9fda69032fc2e4bfd3f ]

This unfortunately comes up in regular intervals and breaks
GPU reset for the engine in question.

The sched.ready flag controls if an engine can't get working
during hw_init, but should never be set to false during hw_fini.

v2: squash in unused variable fix (Alex)

Signed-off-by: Christian König <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
4 files changed