qcacld-3.0: Fix kernel checkpatch warnings in wlan_hdd_power.c

Fix kernel checkpatch warnings in wlan_hdd_power.c

Change-Id: I0a22c2c1ebc86ada69ff271cbd68f2166e08b541
CRs-Fixed: 2024274
diff --git a/core/hdd/src/wlan_hdd_main.c b/core/hdd/src/wlan_hdd_main.c
index 2e8bddf..3d673b2 100644
--- a/core/hdd/src/wlan_hdd_main.c
+++ b/core/hdd/src/wlan_hdd_main.c
@@ -217,6 +217,7 @@
 #endif
 
 /* internal function declaration */
+struct notifier_block hdd_netdev_notifier;
 
 struct sock *cesium_nl_srv_sock;
 #ifdef FEATURE_WLAN_AUTO_SHUTDOWN