staging/lustre/libcfs: removed dead code from libcfs_string

Confirmed by cscope that the functions are not used anymore. A fresh compilation does not yield any errors.

Signed-off-by: Dragos Foianu <dragos.foianu@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>