USB: utilize the bus notifiers

This patch (as1185) makes usbcore take advantage of the bus
notifications sent out by the driver core.  Now we can create all our
device and interface attribute files before the device or interface
uevent is broadcast.

A side effect is that we no longer create the endpoint "pseudo"
devices at the same time as a device or interface is registered -- it
seems like a bad idea to try registering an endpoint before the
registration of its parent is complete.  So the routines for creating
and removing endpoint devices have been split out and renamed, and
they are called explicitly when needed.  A new bitflag is used for
keeping track of whether or not the interface's endpoint devices have
been created, since (just as with the interface attributes) they vary
with the altsetting and hence can be changed at random times.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>