Reset single scan timestamp when disabling Wifi

This timestamp needs to be reset when WiFi is disabled. When WiFi
is enabled again, a connectivity scan starts immediately.
Otherwise it can be delayed because of the minimum periodic single
scan interval rule.

Bug: 28986330
Change-Id: I5a01dc267a05791eba34c87e6d9301bd998bf377
Tests: Wifi unit tests, manual test
1 file changed
tree: b12bcef028c284fa448ea97f4f56722523f70360
  1. service/
  2. tests/