drm/i915/gvt: do not deliver a workload if its creation fails

commit dade58ed5af6365ac50ff4259c2a0bf31219e285 upstream.

in workload creation routine, if any failure occurs, do not queue this
workload for delivery. if this failure is fatal, enter into failsafe
mode.

Fixes: 6d763035 ("drm/i915/gvt: Move common vGPU workload creation into scheduler.c")
Cc: stable@vger.kernel.org #4.19+
Cc: zhenyuw@linux.intel.com
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>