Remove compute stats option from bin/load-data.py

This option is not implemented in this script and doesn't make it
obvious that it doesn't do anything.

Change-Id: I1a1eff38460fd181c486cfca2840108a58e21603
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1059
Reviewed-by: Lenni Kuff <lskuff@cloudera.com>
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: Nong Li <nong@cloudera.com>