Wifi: Use bss->age identifier for wifi scan results

This value will be used as "timestamp" and Google Play Services
uses this value for identifying sane wifi scan items.

The current timestamp (tsf=) has a different meaning, which causes
the Google Location Resolver to ignore all wifi scan entries and
therefore no location can be resolved.

This solution is already done on batched result parsing, but
missing on the traditional scans.

Change-Id: I36a1aeb666379e6a010298f09161e971012db83f