Read Bluetooth interop database entries from settings (1/2)

Interop database entries are stored in the system settings entry
"BluetoothInteropDatabase". The format is a list of entries separated by
";". An entry consists of a BDA fragment, followed by a comma and an
integer representing a feature from interop.h.

Example:
To disable LE secure connections for devices starting with BDA 11:22:33,
use "11:22:33,0".

Bug: 26548845
Change-Id: I6a9fd34f6af4d3bdfcaa0e051eafebdfbf2a4949
(cherry picked from commit 3bc623be)