pk: Fix upload mode when --hoard is not specified
pk: Fix upload mode when --hoard is not specified

- Have hoard_sync_refs() silently succeed if --hoard was not specified on
the command line

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr