drm/amdgpu: move umc ras init to umc block

move umc ras init from ras module to umc block, generic ras module
should pay less attention to specific ras block.

Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>