qemu_hotplug: try harder to eject media

qemu_hotplug: try harder to eject media

Some guests lock the tray and QEMU eject command will simply fail to
eject the media.  But the guest OS can handle this attempt to eject the
media and can unlock the tray and open it. In this case, we should try
again to actually eject the media.

If the first attempt fails to detect a tray_open we will fail with
error, from monitor.  If we receive that event, we know, that the guest
properly reacted to the eject request, unlocked the tray and opened it.
In this case, we need to run the command again to actually eject the
media from the device.  The reason to call it again is, that QEMU
doesn't wait for the guest to react and report an error, that the tray
is locked.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1147471

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>