usb: Remove legacy -usbdevice options (host, serial, disk and net)

usb: Remove legacy -usbdevice options (host, serial, disk and net)

The option have been marked as deprecated since QEMU 2.10, and so far
nobody complained that the host, serial, disk and net options are urgently
required anymore. So let's now get rid at least of this legacy pile, to
simplify the usb code quite a bit.

This patch removes the usbdevices host, serial, disk and net. These devices
use their own complicated parameter parsing mechanisms, so they are just
ugly to maintain, without real benefit for the users (the users can use the
corresponding "-device" parameters instead which have the same complexity
as the "-usbdevice" devices here).

Note that the other rather simple -usbdevice options (mouse, tablet, etc.)
are not removed yet (the code is really simple here, so it does not hurt
much to keep it), as well as the two devices "braille" and "bt" which are
easier to use with -usbdevice than with -device.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-id: 1515519171-20315-1-git-send-email-thuth@redhat.com

[kraxel] delete some usb_host_device_open() leftovers.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>