drm/amdgpu: switch to amdgpu_ras_late_init for nbio v7_4 (v2)

drm/amdgpu: switch to amdgpu_ras_late_init for nbio v7_4 (v2)

call helper function in late init phase to handle ras init
for nbio ip block

v2: init local var r to 0 in case the function return failure
on asics that don't have ras_late_init implementation

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>