ath9k_hw: Add capability flag for Antenna diversity and combining feature

This is enabled only for ar9285.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.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 1601dd4..1a0efbd 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -204,6 +204,7 @@
 	ATH9K_HW_CAP_FASTCLOCK			= BIT(20),
 	ATH9K_HW_CAP_SGI_20			= BIT(21),
 	ATH9K_HW_CAP_PAPRD			= BIT(22),
+	ATH9K_HW_CAP_ANT_DIV_COMB		= BIT(23),
 };
 
 struct ath9k_hw_capabilities {