Merge remote-tracking branch 'amit/master' into staging

Merge remote-tracking branch 'amit/master' into staging

* amit/master:
  virtio-serial-bus: assert port is non-null in remove_port()
  virtio-serial-bus: send_control_msg() should not deal with cpkts
  virtio-serial: delete timer if active during exit
  virtio-serial: allocate post_load only at load-time
  virtio-serial: move active ports loading to separate function
  virtio-serial: use uint32_t to count ports

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>