ath9k: Add a debugfs file for dumping DMA status

Debugfs file location: ath9k/<wiphy>/dma
Contains values in DMA debug registers.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/main.c b/drivers/net/wireless/ath9k/main.c
index 7138964..ac37605 100644
--- a/drivers/net/wireless/ath9k/main.c
+++ b/drivers/net/wireless/ath9k/main.c
@@ -17,6 +17,7 @@
 #include <linux/nl80211.h>
 #include "core.h"
 #include "reg.h"
+#include "hw.h"
 
 #define ATH_PCI_VERSION "0.1"