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: NChristian König <christian.koenig@amd.com>
Fixes: 90b69cdc drm/amdgpu: stop adding VM updates fences to the resv obj
Reviewed-by: Nxinhui pan <xinhui.pan@amd.com>
Tested-by: NLuben Tuikov <luben.tuikov@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>