drm/amdgpu:no gpu scheduler for KIQ

KIQ is used for interaction between driver and
CP, and not exposed to outside client, as such it
doesn't need to be handled by GPU scheduler.

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Signed-off-by: Trigger Huang <trigger.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>