arm: pci addressing, keyboard and ehci controller

arm: pci addressing, keyboard and ehci controller

On arm we start off with a pcie bridge pcie.0. We need a
keyboard in addition to the tablet device, and we need to
connect both to an 'ehci' controller.

To do all this, we also pass the $arch variable through a
whole lot of function calls to ultimately also adapt the
hotplug code to take care of the new keyboard device.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>