PCIDevice::rom_file is leaked.
PCIDevice::rom_file is allocated in pci_qdev_init(), but not freed anywhere.
free it in qemu_unregister_device().
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>