blobtool: Move I/O loop to a helper function
blobtool: Move I/O loop to a helper function

- Move outer I/O loop to a helper function

- Add infp/outfp members to struct iodata

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