The new AFSInitCcb() allocates its own DirOpenReferenceCount to
associate with the AFSCcb.DirectoryCB.
It also accepts the GrantedAccess mask and the FileAccess values
which are stored in the AFSCcb.
These changes simplify the callers and remove responsibility of
tracking whether or not the DirOpenReferenceCount was successfully
associated with the AFSCcb.
The allocated DirOpenReferenceCount is always released by
AFSRemoveCcb().