Bluetooth: Fix double scan updates

When disable/enable scan command is issued twice, some controllers
will return an error for the second request, i.e. requests with this
command will fail on some controllers, and succeed on others.

This patch makes sure that unnecessary scan disable/enable commands
are not issued.

When adding device to the auto connect whitelist when there is pending
connect attempt, there is no need to update scan.

hci_connect_le_scan_cleanup is conditionally executing
hci_conn_params_del, that is calling hci_update_background_scan. Make
the other case also update scan, and remove reduntand call from
hci_connect_le_scan_remove.

When stopping interleaved discovery the state should be set to stopped
only when both LE scanning and discovery has stopped.

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