fuzzy_fastboot: use 'tcp:' prefix to identify fastboot protocol. am: 767fe1515a am: 9c2f03b906 am: 224d06fa1a

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

Change-Id: I808ca7d9897603cc4a067aa6966ee76f48144161