Bluetooth: Use hci_update_random_address() for enabling advertising

When we enable advertising we need to update the local random address if
necessary. This patch takes advantage of the hci_update_random_address()
function to set the own_address_type variable and to update the local
random address if necessary.

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