Notify scan-only mode to driver for power saving

If Wi-Fi driver knows it's in scan-only mode, it can save more power
than connect mode.

This change adds setScanMode in IWifiStaIface to allow Wi-Fi framework
to notify scan-only mode change to Wi-Fi driver.

Bug: 177811719
Test: atest VtsHalWifiV1_5TargetTest

Change-Id: I1dfbc24a0a3272c1341223aff36656be4a6fd21b
4 files changed