fuzzy_fastboot: use 'tcp:' prefix to identify fastboot protocol. am: 767fe1515a am: 9c2f03b906

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/core/+/12448097

Change-Id: I82069a7f289a340351280bb18cd5af8ffa6f01b1