Pno frequency culling: Settings.Global flag

Add a flag to enable/disable this feature.

Bug: 64312268
Test: compile
Test: First use "adb shell settings put global wifi_pno_frequency_culling_enabled 1" to test turning on the feature.
Test: Then test "adb shell settings put global
wifi_pno_frequency_culling_enabled garbage" does not turn the feature
off.
Change-Id: Ia6cd0d3c9888d7b2e0513b51fc4ad92c3eb171de
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index 182f189..dd80cd1 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -485,6 +485,7 @@
                     Settings.Global.WIFI_IDLE_MS,
                     Settings.Global.WIFI_IS_UNUSABLE_EVENT_METRICS_ENABLED,
                     Settings.Global.WIFI_LINK_SPEED_METRICS_ENABLED,
+                    Settings.Global.WIFI_PNO_FREQUENCY_CULLING_ENABLED,
                     Settings.Global.WIFI_MAX_DHCP_RETRY_COUNT,
                     Settings.Global.WIFI_MOBILE_DATA_TRANSITION_WAKELOCK_TIMEOUT_MS,
                     Settings.Global.WIFI_NETWORK_SHOW_RSSI,