USB: make usbdevices export their device nodes instead of using a separate class

USB: make usbdevices export their device nodes instead of using a separate class

o The "real" usb-devices export now a device node which can
  populate /dev/bus/usb.

o The usb_device class is optional now and can be disabled in the
  kernel config. Major/minor of the "real" devices and class devices
  are the same.

o The environment of the usb-device event contains DEVNUM and BUSNUM to
  help udev and get rid of the ugly udev rule we need for the class
  devices.

o The usb-devices and usb-interfaces share the same bus, so I used
  the new "struct device_type" to let these devices identify
  themselves. This also removes the current logic of using a magic
  platform-pointer.
  The name of the device_type is also added to the environment
  which makes it easier to distinguish the different kinds of devices
  on the same subsystem.

  It looks like this:
    add@/devices/pci0000:00/0000:00:1d.1/usb2/2-1
    ACTION=add
    DEVPATH=/devices/pci0000:00/0000:00:1d.1/usb2/2-1
    SUBSYSTEM=usb
    SEQNUM=1533
    MAJOR=189
    MINOR=131
    DEVTYPE=usb_device
    PRODUCT=46d/c03e/2000
    TYPE=0/0/0
    BUSNUM=002
    DEVNUM=004

This udev rule works as a replacement for usb_device class devices:
  SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", \
    NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0644"

Updated patch, which needs the device_type patches in Greg's tree.

I also got a bugzilla assigned for this. :)
  https://bugzilla.novell.com/show_bug.cgi?id=250659

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>