cifs: remove cifsInodeInfo->inUse counter

It was purported to be a refcounter of some sort, but was never
used that way. It never served any purpose that wasn't served equally well
by the I_NEW flag.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>