floss: Handle unaligned bt_property_t data

The void* inside bt_property_t may point to an unaligned memory block,
thus read_unaligned is needed.

Bug: 302485558
Tag: #floss
Test: mmm -j packages/modules/Bluetooth
Test: Follow the bug repro steps, Floss can be enabled successfully
Test: no crash running bluetooth_AdapterQuickHealth.AVL.all_floss
Change-Id: Ia09bce99aa6159fc5e017b7a0870c692772f0d43