ath9k-htc:respect usb buffer cacheline alignment in ath9k_hif_usb_alloc_rx_urbs

In ath9k_hif_usb_alloc_rx_urbs, ath9k-htc will pass skb->data into
usb hcd and usb hcd will do dma mapping and unmapping to the buffer
pointed by skb->data, so we should pass a cache-line aligned address.

This patch replace __dev_alloc_skb with alloc_skb to make skb->data
pointed to a cacheline aligned address simply since ath9k-htc does not
skb_push on the skb and pass it to mac80211, also use kfree_skb to free
the skbs allocated by alloc_skb(we can use kfree_skb safely in hardirq
context since skb->destructor is NULL always in the path).

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/hif_usb.c

@@ -467,7 +467,7 @@ resubmit:
 
 	return;
 free:
-	dev_kfree_skb_any(skb);
+	kfree_skb(skb);
 }
 
 static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
@@ -625,7 +625,7 @@ static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 		}
 
 		/* Allocate buffer */
-		skb = __dev_alloc_skb(MAX_RX_BUF_SIZE, GFP_KERNEL);
+		skb = alloc_skb(MAX_RX_BUF_SIZE, GFP_KERNEL);
 		if (!skb) {
 			ret = -ENOMEM;
 			goto err_skb;
@@ -657,7 +657,7 @@ static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 	return 0;
 
 err_submit:
-	dev_kfree_skb_any(skb);
+	kfree_skb(skb);
 err_skb:
 	usb_free_urb(urb);
 err_urb: