Fix v2 format decoding in btsnooz.py

The delta_time_ms field now seems to be 64 bits instead of 32. Without
this change, dumps fail to decode and the script exits with a TypeError
because type_to_hci encounters an unknown packet type.

Bug: 175283029
Test: ./btsnooz.py bugreport-WXYZ.txt
Tag: #refactor
Sponsor: optedoblivion@
Change-Id: Ib893ee63abacf5335a4cbabb1dbdfc1702da77e6