Currently there is no way to restart le scan, and it's needed in
service scan method. The way it work: it disable, and then enable le
scan on controller.

During the restart, we must remember when the scan was started, and
it's duration, to later re-schedule the le_scan_disable work, that was
stopped during the stop scan phase.
Signed-off-by: NJakub Pawlowski <jpawlowski@google.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>