usb4bsd: Allow some parts to be built into the kernel.

usb4bsd: Allow some parts to be built into the kernel.

This is for the core support, and for uhci, ohci, ehci and xhci.

To do this, replace:

  device usb

with

  device "usb4bsd"

in the config. The quotes are needed at the moment to cope with a
weakness in our config(8) that needs fixing.

Based-on-patch-submitted-by: Markus Pfeiffer <markus.pfeiffer@morphism.de>