DGWIFI_2_1 Beacon Rx count for linux platform (#32963)

* added condition for beacon Rx count in DiagnosticDataProviderImpl

* Restyled by clang-format

---------

Co-authored-by: Restyled.io <commits@restyled.io>
diff --git a/src/platform/Linux/DiagnosticDataProviderImpl.cpp b/src/platform/Linux/DiagnosticDataProviderImpl.cpp
index 3802d96..74f7003 100644
--- a/src/platform/Linux/DiagnosticDataProviderImpl.cpp
+++ b/src/platform/Linux/DiagnosticDataProviderImpl.cpp
@@ -761,9 +761,12 @@
 
 CHIP_ERROR DiagnosticDataProviderImpl::GetWiFiBeaconRxCount(uint32_t & beaconRxCount)
 {
-    beaconRxCount = mBeaconRxCount;
-
-    return CHIP_NO_ERROR;
+    if (DeviceLayer::ConnectivityMgrImpl().IsWiFiManagementStarted())
+    {
+        beaconRxCount = mBeaconRxCount;
+        return CHIP_NO_ERROR;
+    }
+    return CHIP_ERROR_NOT_IMPLEMENTED;
 }
 
 CHIP_ERROR DiagnosticDataProviderImpl::ResetWiFiNetworkDiagnosticsCounts()