drm/amdgpu: Prevent any job recoveries after device is unplugged.

Return DRM_TASK_STATUS_ENODEV back to the scheduler when device
is not present so they timeout timer will not be rearmed.

v5: Update to match updated return values in enum drm_gpu_sched_stat

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210512142648.666476-12-andrey.grodzovsky@amd.com