ath9k_hw: Add abstraction to set/get link pointer

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/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 7219e29..4f12de9 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -665,7 +665,7 @@
 		bpad = PADBYTES(al_delta) + (ndelim << 2);
 
 		bf->bf_next = NULL;
-		bf->bf_desc->ds_link = 0;
+		ath9k_hw_set_desc_link(sc->sc_ah, bf->bf_desc, 0);
 
 		/* link buffers of this frame to the aggregate */
 		ath_tx_addto_baw(sc, tid, bf);
@@ -673,7 +673,8 @@
 		list_move_tail(&bf->list, bf_q);
 		if (bf_prev) {
 			bf_prev->bf_next = bf;
-			bf_prev->bf_desc->ds_link = bf->bf_daddr;
+			ath9k_hw_set_desc_link(sc->sc_ah, bf_prev->bf_desc,
+					       bf->bf_daddr);
 		}
 		bf_prev = bf;
 
@@ -1659,7 +1660,7 @@
 	list_add_tail(&bf->list, &bf_head);
 
 	ds = bf->bf_desc;
-	ds->ds_link = 0;
+	ath9k_hw_set_desc_link(ah, ds, 0);
 
 	ath9k_hw_set11n_txdesc(ah, ds, bf->bf_frmlen, frm_type, MAX_RATE_POWER,
 			       bf->bf_keyix, bf->bf_keytype, bf->bf_flags);