Leave the USB keyboard registered with the keyboard subsystem even if the

Leave the USB keyboard registered with the keyboard subsystem even if the
USB keyboard is unplugged or reset.  USB keyboard resets can occur under a
number of conditions, including during system boot and when other devices
on the same controller are pulled or create problems for the controller.  If
we were to deregister the keyboard then the console would disconnect from it
and the keyboard would become unusable.

Use the new keyboard preference feature and give a USB keyboard a higher
priority then a standard atkbd keyboard.  ATKBD keyboards often probe even
when no keyboard exists, especially if the BIOS was set to USB keyboard
compatibility mode.  This way if there is a USB keyboard connected up, it
will get priority over the AT keyboard even if the system thinks an AT
keyboard exists.