ath9k|ath9k_htc: move IEEE80211_MS_TO_TU to common

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/common.h b/drivers/net/wireless/ath/ath9k/common.h
index 26aafb3..8deed82 100644
--- a/drivers/net/wireless/ath/ath9k/common.h
+++ b/drivers/net/wireless/ath/ath9k/common.h
@@ -44,6 +44,8 @@
 #define ATH_EP_RND(x, mul) 						\
 	(((x) + ((mul)/2)) / (mul))
 
+#define IEEE80211_MS_TO_TU(x)   (((x) * 1000) / 1024)
+
 struct ath_beacon_config {
 	int beacon_interval;
 	u16 dtim_period;