drm/amdgpu: add sdma 4.2.2 header files for Arcturus

SDMA is the system DMA block.

Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>