virtio-gpu: fix memory leak in virtio_gpu_resource_create_2d

In virtio gpu resource create dispatch, if the pixman format is zero
it doesn't free the resource object allocated previously. Thus leading
a host memory leak issue. This patch avoid this.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 57df486e.8379240a.c3620.ff81@mx.google.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/display/virtio-gpu.c

@@ -333,6 +333,7 @@ static void virtio_gpu_resource_create_2d(VirtIOGPU *g,
         qemu_log_mask(LOG_GUEST_ERROR,
                       "%s: host couldn't handle guest format %d\n",
                       __func__, c2d.format);
+        g_free(res);
         cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
         return;
     }