[PATCH] cfg80211: Fix for crash in cfg80211

[Srinivasan B <srinivasanb@posedge.com>]

Patch Description:
                     cfg80211 module crashes when cfg80211 & mac80211 
loaded and unloading lmac driver.

Scenario Explanation:
                     (Step 1) : cfg80211, mac80211 and lmac driver 
modules are loaded initially.
                     (Step 2) : unload the lmac driver.
                                     then any dev calls to stack causes 
the crash.
Code Changes:
                     dev->ethtools_ops is assigned during 
NETDEV_REGISTER and the same can be cleared during NETDEV_UNREGISTER.

Signed-off-by: Srinivasan Chandrasekaran <srinivasb@posedge.com>
---

diff --git a/net/wireless/core.c b/net/wireless/core.c
index dcd64d5..74bb7c4 100755
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -944,6 +944,10 @@ static int cfg80211_netdev_notifier_call(struct 
notifier_block *nb,
  #endif
          }
          mutex_unlock(&rdev->devlist_mtx);
+
+        if (dev->ethtool_ops)
+            dev->ethtool_ops = NULL;
+
          /*
           * synchronise (so that we won't find this netdev
           * from other code any more) and then clear the list