qcacld-3.0: Fix wlan load failure

CONFIG_GENL is not defined in some target
builds which is causing wlan load failure
with deubg message unknown symbol.

Fix the build load failures.

Change-Id: I448e405b099788c4c83303d9abdee9f7c1e45261
CRs-Fixed: 2188593

core/hdd/src/wlan_hdd_spectralscan.c

@@ -479,4 +479,9 @@ int spectral_scan_activate_service(void)
 				spectral_scan_msg_handler, NULL);
 	return 0;
 }
+#else
+int spectral_scan_activate_service(void)
+{
+	return 0;
+}
 #endif