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
diff --git a/wifi/1.5/IWifiStaIface.hal b/wifi/1.5/IWifiStaIface.hal
index e9d411e..daf545e 100644
--- a/wifi/1.5/IWifiStaIface.hal
+++ b/wifi/1.5/IWifiStaIface.hal
@@ -41,4 +41,17 @@
      * @return stats Instance of |LinkLayerStats|.
      */
     getLinkLayerStats_1_5() generates (WifiStatus status, StaLinkLayerStats stats);
+
+    /**
+     * Turn on/off scan only mode for the interface.
+     *
+     * @param enable Indicate if scan only mode is to be turned on/off.
+     * @return status Status of the operation.
+     *         Possible status codes:
+     *         |WifiStatusCode.SUCCESS|,
+     *         |WifiStatusCode.ERROR_NOT_SUPPORTED|,
+     *         |WifiStatusCode.ERROR_WIFI_IFACE_INVALID|,
+     *         |WifiStatusCode.FAILURE_UNKNOWN|
+     */
+    setScanMode(bool enable) generates (WifiStatus status);
 };