drm/amdgpu: implement more ib pools (v2)

We have three ib pools, they are normal, VM, direct pools.

Any jobs which schedule IBs without dependence on gpu scheduler should
use DIRECT pool.

Any jobs schedule direct VM update IBs should use VM pool.

Any other jobs use NORMAL pool.

v2: squash in coding style fix

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