drm/amdgpu: add VM update fences back to the root PD v2

drm/amdgpu: add VM update fences back to the root PD v2

Add update fences to the root PD while mapping BOs.

Otherwise PDs freed during the mapping won't wait for
updates to finish and can cause corruptions.

v2: rebased on drm-misc-next

Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: 459ca02cfe43e drm/amdgpu: stop adding VM updates fences to the resv obj
Reviewed-by: xinhui pan <xinhui.pan@amd.com>
Tested-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>