drm/amdgpu: Add fatal error handling in nbio v4_3

GPU will stop working once fatal error is detected.
it will inform driver to do reset to recover from
the fatal error.

v2: squash in logic fix (Srinivasan)
v3: squash in logic fix (Dan)

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Candice Li <candice.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>