mwifiex: add NULL checks in driver unload path

If driver load is failed, sometimes few pointers may remain
uninitialized ex. priv->wdev, priv->netdev, adapter->sleep_cfm
This will cause NULL pointer dereferance while unloading the
driver.
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kiran Divekar <dkiran@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/init.c

@@ -382,7 +382,8 @@ mwifiex_free_adapter(struct mwifiex_adapter *adapter)
 
 	adapter->if_ops.cleanup_if(adapter);
 
-	dev_kfree_skb_any(adapter->sleep_cfm);
+	if (adapter->sleep_cfm)
+		dev_kfree_skb_any(adapter->sleep_cfm);
 }
 
 /*

drivers/net/wireless/mwifiex/main.c

@@ -822,7 +822,9 @@ int mwifiex_remove_card(struct mwifiex_adapter *adapter, struct semaphore *sem)
 			continue;
 
 		rtnl_lock();
-		mwifiex_del_virtual_intf(priv->wdev->wiphy, priv->netdev);
+		if (priv->wdev && priv->netdev)
+			mwifiex_del_virtual_intf(priv->wdev->wiphy,
+						 priv->netdev);
 		rtnl_unlock();
 	}
 
@@ -830,9 +832,11 @@ int mwifiex_remove_card(struct mwifiex_adapter *adapter, struct semaphore *sem)
 	if (!priv)
 		goto exit_remove;
 
-	wiphy_unregister(priv->wdev->wiphy);
-	wiphy_free(priv->wdev->wiphy);
-	kfree(priv->wdev);
+	if (priv->wdev) {
+		wiphy_unregister(priv->wdev->wiphy);
+		wiphy_free(priv->wdev->wiphy);
+		kfree(priv->wdev);
+	}
 
 	mwifiex_terminate_workqueue(adapter);