drm/amdgpu: Clear RAS interrupt status on aldebaran

resolve register address issue for detecting/clearing RAS interrupt

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>