floss: topshim: gatt: Remove unnecessary type convert

For some trivial types we can reuse the bindgen-ed definition in Rust
and pass them directly to LibBluetooth.

Bug: 343675216
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: bluetooth_AdapterQuickHealth.AVL.all_floss
Test: NearbyShare / PhoneHub / SmartLock / FastPair
Flag: EXEMPT, Floss-only changes
Change-Id: Ic4c909a2ce04a6125d693a6fc625184af9557db3