RootCanal: Fix bd address used for HCI sniffer file names

Regression introduced in I8d59dca134a2a10e85073d1b7d6ed8c2e41e783c
Because the device is added in an async event, the device address
is not available when the PCAP file is opened, and the default
bluetooth address is used.

Bug: 278891939
Test: ./root-canal --enable_hci_sniffer
Change-Id: Ic3eed88575a5b9180e0b42f798a305a26e59721a