1. expand the USB_ATTACH_SETUP macro (requested by jmcneill)
2. reorder the attach function so that the first thing it does is print
newlines.
3. after this, we can call usbd_devinfo_alloc(), which polls the device
allowing a context switch, and aprint_normal() the device information.
this avoids problems where autoconf messages are getting mixed up.
Register _childdetached methods with drivers that attach children.
Wait to set child references to NULL there, instead of doing that
in the detach method.
Replace many uses of USB_DECLARE_DRIVER() with CFATTACH_DECL2().
matching (and handling) a whole device and those which match an
interface only. This will allow to enforce some rules, eg that
the former don't use interface information for matching or that the
latter don't modify global device state.
The previous way left too much freedom do the drivers which led to
inconsistencies and abuse.
For now, I've not changed locators and submatch rules, this will
happen later.
There should not be any change in behaviour, except in the case of
some drivers which did behave inconsistently:
if_atu, if_axe, uep: matched the configured device in the interface
stage, but did configuration again. I've converted them to match
in the device stage.
ustir, utoppy: matched in the interface stage, but only against
vendor/device information, and used any configuration/interface
without checking. Changed to match in device stage, and added
some simple code to configure and use the first interface.
If you have one of those devices, please test!
