[pve-devel] usb2.0 as default + usb-tablet hotplug/unplug

[Alexandre Derumier]

usb2.0 as default + usb-tablet hotplug/unplug

- This add ehci as default usb controller. (always activated)
- Full usb2 withtout usb1 compagnon (Don't need anymore the external usb.cfg) as we don't need usb1 anymore

- hotplug/unplug usb-tablet on console task start/stop.

tablet config: 
 tablet:0  no tablet
 tablet:1  always tablet
 no config : auto hotplug/unplug at console task


On my old xeon, tablet on usb2 give me 2% less cpu.
Unplugging the tablet give me 6% less cpu.