iwlagn: keep track of failure tx status

Tx command response sent to host by uCode after completed
the transmission attempt. The status parameter indicates
whether the transmission was successful, or else why if failed.

Here we keep the counters to help understand the different failure
cases.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-debugfs.h b/drivers/net/wireless/iwlwifi/iwl-agn-debugfs.h
index bbdce59..f2573b5 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-debugfs.h
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-debugfs.h
@@ -39,6 +39,8 @@
 				     size_t count, loff_t *ppos);
 ssize_t iwl_ucode_bt_stats_read(struct file *file, char __user *user_buf,
 				size_t count, loff_t *ppos);
+ssize_t iwl_reply_tx_error_read(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos);
 #else
 static ssize_t iwl_ucode_rx_stats_read(struct file *file, char __user *user_buf,
 				       size_t count, loff_t *ppos)
@@ -60,4 +62,9 @@
 {
 	return 0;
 }
+static ssize_t iwl_reply_tx_error_read(struct file *file, char __user *user_buf,
+				       size_t count, loff_t *ppos)
+{
+	return 0;
+}
 #endif