drm/amdgpu:invoke CSA functions (v2)

Make sure the CSA is mapped.

v2: agd: rebase.

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>