drm/i915: unpin on error in intel_vgpu_shadow_mm_pin()

Call intel_vgpu_unpin_mm() on this error path.

Fixes: 4187414 ("drm/i915/gvt: Adding ppgtt to GVT GEM context after shadow pdps settled.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/Y3OQ5tgZIVxyQ/WV@kili
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>

Author: error27

drivers/gpu/drm/i915/gvt/scheduler.c

@@ -695,6 +695,7 @@ intel_vgpu_shadow_mm_pin(struct intel_vgpu_workload *workload)
 
 	if (workload->shadow_mm->type != INTEL_GVT_MM_PPGTT ||
 	    !workload->shadow_mm->ppgtt_mm.shadowed) {
+		intel_vgpu_unpin_mm(workload->shadow_mm);
 		gvt_vgpu_err("workload shadow ppgtt isn't ready\n");
 		return -EINVAL;
 	}