Fix xenbus to cause surprise removals for vusb device on removal.

The Windows front end vusb driver expects to be removed via a
surprise removal. The existing code was trying to do an eject
which was not causing the front end driver to finish cleaning up
the device that was removed. Custom code for surprise removal was
only added for vusb devices to prevent injuring the already delicate
shutdown/removal code for other types of devices.

OXT-35

Signed-off-by: Ross Philipson ross.philipson@gmail.com
Fix xenbus to not re-enumerate closed VUSB devices.

When VUSB devices are removed, they are just gone for good. There
is no possibility of a reconnect. This fix detects the backend state
went to closed which means the device was there and gone. In this
case, xenbus just ignores the closed device. The usbowls thingy can
then properly clean up the mess in xenstore.

OXT-35

Signed-off-by: Ross Philipson ross.philipson@gmail.com
VUSB moved reconnect check one block out.

OXT-35

Signed-off-by: Ross Philipson <ross.philipson@gmail.com>
Merge pull request #12 from rossphilipson/master

Fix xenbus to cause surprise removals for vusb device on removal.