Bluetooth: Fix toggling background scan when changing connectable state

If the connectable state change doesn't require any special HCI commands
the set_connectable_update_settings() function is used instead of the
set_connectable_complete() function. We must therefore make sure to call
hci_update_background_scan() there as well. This code path is used also
when we're powered off, but that's fine since hci_update_background_scan()
has the necessary checks for it.

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