drm/amdgpu/sdma6: update mqd init for UQ

Set the addresses for the UQ metadata.

V2: Fix lower address mask (Shashank)
V3: Use lower_32_bits for MQD objects (Alex)

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>