Get device type using adv flag data

Device type is incorrectly set to LE only if flag data is missing.
The CL does the following to set the device type:
1. If adv is connectable and flag data is not present, it is DUAL mode.
2. If adv is not connectable and flag data is not present, it is
   UNKNOWN.
3. If flag data is present, use `BR/EDR Not Supported` bit

Bug: 273890240
Tag: #refactor
Test: manual

Change-Id: I773680f865e3f786e6b9805568e93aa72f10a799