drm/amdgpu: initialize new parameters and functions for amdgpu_umc structure

add initialization for new members of amdgpu_umc structure

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