ath9k: Add debugfs file for RX errors

This file can be used to track frame reception errors.
PHY error counts are also added.

Location: ath9k/phy#/recv

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/recv.c

@@ -571,6 +571,8 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
 		hw = ath_get_virt_hw(sc, hdr);
 		rx_stats = &ds->ds_rxstat;
 
+		ath_debug_stat_rx(sc, bf);
+
 		/*
 		 * If we're asked to flush receive queue, directly
 		 * chain it back at the queue without processing it.