drm/amdgpu: Update RAS init handling

Output RAS init status

If RAS init fails, teardown RAS context

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: John Clements <john.clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>