ath9k: Gather and report IRQ sync_cause errors.

Report all defined sync_cause errors in debugfs
to aid with debugging.

Use a macro to print out the interrupts file contents
to decrease code duplication.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
index 1d4b983..dd4b8f4 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -956,6 +956,12 @@
 
 bool ath9k_hw_setpower(struct ath_hw *ah, enum ath9k_power_mode mode);
 
+#ifdef CONFIG_ATH9K_DEBUGFS
+void ath9k_debug_sync_cause(struct ath_common *common, u32 sync_cause);
+#else
+static void ath9k_debug_sync_cause(struct ath_common *common, u32 sync_cause) {}
+#endif
+
 /* Generic hw timer primitives */
 struct ath_gen_timer *ath_gen_timer_alloc(struct ath_hw *ah,
 					  void (*trigger)(void *),