btmgmt_protocol: Fix unhandled exception when decoding EIRData

[martin-flaska]

ValueError: 0 is not a valid ADType

This is to fix an unhandled exception when receiving unsupported / invalid ADType value (0 - in my case).

Discussed also in this reported issue: #13

I am not sure about the error message complexity, but in a case it happens rarely, it could be helpful.

An error log example:

2025-06-19 19:28:05,465 [  ERROR] btsocket.btmgmt_protocol: Packet.decode: failed to decode eir_data as EIRData. Offset: 14, width: 65535, pkt: c1 ce 55 1c 5e 68 01 9c 00 00 00 00 1f 00 02 01 06 1b 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 f0 ff. Error: EIRData.decode: Invalid ADType: 0x00, data len: 31, data: 1b 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 f0 ff