floss: Replace unwrap with match to prevent crash

This should help us to get more meaningful warning and prevent crash
when something unexpected happens.

Bug:243821388
Tag: #floss
Test: Build and verify a2dp, hfp, avrcp all works
BYPASS_LONG_LINES_REASON: Bluetooth likes 120 char lines

Change-Id: I25f38e14698f8a78a13e226130286edc2e7d5618