drm/amdgpu: fix find ras error node error

the origin function might return the wrong node.

Fixes: 5b1270be

 ("drm/amdgpu: add ras_err_info to identify RAS error source")
Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>