Windows: after dir enum adjust dir scache LRU

Windows: after dir enum adjust dir scache LRU

During a directory enumeration the directory scache object
is reference counted so it can't be recycled.  However, if
there are more directory entries than the maximum number
of cached scache objects the directory scache object will
end up being the next object to be recycled after the refcount
is dropped.  Since the directory is clearly a hot object, before
dropping the reference, adjust the scache LRU position so that
it is the last object to be recycled.

Fix the variable name for the directory scache to be 'dscp'
for consistency.

Change-Id: Ia2089fb9b47dab77abc0911ab009e5aed75ed848
Reviewed-on: http://gerrit.openafs.org/5158
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>