ath9k: Fix regression in LNA diversity

The commit "ath9k: Optimize LNA check" tried
to use the "rs_firstaggr" flag to optimize the LNA
combining algorithm when processing subframes in
an A-MPDU. This doesn't appear to work well in practice,
so revert it and use the old method of relying on
"rs_moreaggr".

Cc: stable@vger.kernel.org # 3.11
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 4ee472a..ab9e3a8 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -1270,13 +1270,6 @@
 		return;
 
 	/*
-	 * All MPDUs in an aggregate will use the same LNA
-	 * as the first MPDU.
-	 */
-	if (rs->rs_isaggr && !rs->rs_firstaggr)
-		return;
-
-	/*
 	 * Change the default rx antenna if rx diversity
 	 * chooses the other antenna 3 times in a row.
 	 */