st/vdpau: Fix memory leak in vlVdpOutputSurfaceCreate.

Fixes resource leak defect reported by Coverity.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Christian König <christian.koenig@amd.com>

src/gallium/state_trackers/vdpau/output.c

@@ -86,6 +86,7 @@ vlVdpOutputSurfaceCreate(VdpDevice device,
    if (!res) {
       pipe_mutex_unlock(dev->mutex);
       FREE(dev);
+      FREE(vlsurface);
       return VDP_STATUS_ERROR;
    }