Current hcd-ohci does not handle DMA errors. However they may happen
so here we introduce simple error handling.

On such errors, a typical OHCI will stop operating, signal the guest
about the error by sending "UnrecoverableError Event", set itself into
error state and set "Detected Parity Error" in its PCI config space
to signal that it got an error and so does the patch.

This also adds ohci_die() call to ohci_bus_start() to handle possible
failure of qemu_new_timer_ns().
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>