iwmc3200wifi: fix NULL pointer dereference in iwm_if_free

The driver private data is now based on wiphy. So we should not
touch the private data after wiphy_free() is called. The patch
fixes the potential NULL pointer dereference by making the
iwm_wdev_free() the last one on the interface removal path.
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwmc3200wifi/netdev.c

@@ -151,8 +151,8 @@ void iwm_if_free(struct iwm_priv *iwm)
 		return;
 
 	free_netdev(iwm_to_ndev(iwm));
-	iwm_wdev_free(iwm);
 	iwm_priv_deinit(iwm);
+	iwm_wdev_free(iwm);
 }
 
 int iwm_if_add(struct iwm_priv *iwm)