Enable pipes on both MECs for MES.

Fixes: 745f46b6 ("drm/amdgpu: enable mes v12 self test")
Acked-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Prike Liang <Prike.Liang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>