fix(writer): Fix succeeded flash count in progress state
fix(writer): Fix succeeded flash count in progress state

This fixes a bug where succeeded flashes could become negative due to
improper math

Change-Type: patch

resin-io/etcher,resin-io/resin-etcher,resin-io/etcher,resin-io/herostratus,resin-io/resin-etcher,resin-io/etcher,resin-io/etcher,resin-io/etcher,resin-io/herostratus