drm/amdgpu/mes: zero the sdma_hqd_mask of 2nd SDMA engine for SDMA 6.0.1

there is only one SDMA engine in SDMA 6.0.1, the sdma_hqd_mask has to be
zeroed for the 2nd engine, otherwise MES scheduler will consider 2nd
engine exists and map/unmap SDMA queues to the non-existent engine.

Signed-off-by: Yifan Zhang <yifan1.zhang@amd.com>
Reviewed-by: Tim Huang <Tim.Huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>