Bluetooth: Provide defaults for LE connection latency and timeout

Store the connection latency and supervision timeout default values
with all the other controller defaults. And when needed use them
for new connections.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

diff --cc include/net/bluetooth/hci_core.h
Simple merge

diff --cc net/bluetooth/hci_conn.c
Simple merge

diff --cc net/bluetooth/hci_core.c
Simple merge