windows: Crash when the handle communication device cannot be found

windows: Crash when the handle communication device cannot be found

When trying to uninstall/disable the OVS extension the driver will
fail to unload properly(require reboot)/hang until ovs-vswitchd is closed.

The root cause of this behavior is because the handles from ovs-vswitchd
to the kernel communication devices are still opened although the
actual device was removed from the kernel.

Trying to close the handles will also fail because they do not exist.

The remaining option is to cause a crash and rely on the service manager
to restart ovs-vswitchd.

Reported-at: https://github.com/openvswitch/ovs-issues/issues/27
Reported-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>