Windows: afslogon.dll is not a file system interface

Windows: afslogon.dll is not a file system interface

Do not return a file system network type that corresponds
to a real file system inter since afslogon is in fact not
associated with a file system interface.  We can't return
WNNC_NET_NONE (0) because that prevents NPLogonNotify()
from being executed.  However, if we return an in use
file system value that can confuse the system when the
actual file system's network provider is also installed.

Change-Id: I845bc633f17f21946ce7de796d66c0bb429005cd
Reviewed-on: http://gerrit.openafs.org/5313
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>