Bluetooth: Move get info completed callback to a2mp.c

To avoid a2mp module hooks from hci_event.c and send
getinfo response operation only required by a2mp module,
we can move this callback to a2mp.c

Signed-off-by: Arron Wang <arron.wang@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>