iwlwifi: make iwl_tx_queue->tfds void*

Instead of having both tfds and tfds39, we can just have a void *tfds.
It makes the tx_queue structure nicer, and the code cleaner. It also helps
with further TX queues management code merging.

Signed-off-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index 79f2d45..78ce4f4 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -149,8 +149,7 @@
 
 struct iwl_tx_queue {
 	struct iwl_queue q;
-	struct iwl_tfd *tfds;
-	struct iwl3945_tfd *tfds39;
+	void *tfds;
 	struct iwl_cmd *cmd[TFD_TX_CMD_SLOTS];
 	struct iwl_tx_info *txb;
 	u8 need_update;