InitialLockSetupHelper: fix chars <=> bytes conversion am: d890ee393b am: d4969d6e72

Original change: https://android-review.googlesource.com/c/platform/frameworks/opt/car/setupwizard/+/2700613

Change-Id: Icb42209225dfa40430e62d5e7e4b32cefbe75ae1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>