Bluetooth: hci_conn: Always use sk_timeo as conn_timeout

This aligns the use socket sk_timeo as conn_timeout when initiating a
connection and then use it when scheduling the resulting HCI command,
that way the command is actually aborted synchronously thus not
blocking commands generated by hci_abort_conn_sync to inform the
controller the connection is to be aborted.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>