drm/amdgpu/gfx8: add support kernel interface queue(KIQ)

KIQ is queue-memory based initialization method: setup KIQ queue
firstly, then send command to KIQ to setup other queues, without
accessing registers.

For virtualization, need KIQ to access virtual function registers
when running on guest mode.

V2: use amdgpu_bo_create/free_kernel to allocate BO.

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>