This mostly moves the initialization of some sysfs-related
fields earlier, so HCD code can access them during those
(initial error prone) parts of enumeration without oopsing.

The particular access I wanted was using <linux/driver.h>
debug utilities like dev_dbg(), dev_warn() and so on ... so
I also changed the name the "generic" driver gives itself
to be "usb" so those messages make more sense.

Also added comments about how usb_new_device() moves the
device through the other chapter 9 usb device states.