Bluetooth: mgmt: program multi-adv on power on

Advertising instances programmed while powered off should be advertised
once the device is powered. This patch ensures that all combinations
of setting and/or adding advertising configuration while powered off
will be correctly activated on power on.

Signed-off-by: Florian Grandel <fgrandel@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>