Set "WiFi discovery" bit of device flags according state of Hosted SSID. Return true only if device is hosting AP or if flags are being generated for SSID. BUG:25597839 Change-Id: Idca4f3dbb915e7af0375832260f8280a6b7b08b1 Reviewed-on: https://weave-review.googlesource.com/1529 Reviewed-by: Alex Vakulenko <avakulenko@google.com>