Implement onPeriodChanged and multiple scans of same channels

This change fixes multiple scans of same channels; and it generates
onPeriodChanged event.

cherry-picked from partner:klp-wireless-dev
SHA1 950564a305865cc0ae2bc528479ea6922efbb898

Bug: 15000051
Change-Id: I06a4ecc9d45eda4984de50b97b39f623dd0b26d1
1 file changed