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>
6 files changed