ath9k-htc:respect usb buffer cacheline alignment in reg in path

In ath9k-htc register in path, 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 skb 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>
diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index 24d7b88..d1fa5bd 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -374,7 +374,10 @@
 	epid = htc_hdr->endpoint_id;
 
 	if (epid >= ENDPOINT_MAX) {
-		dev_kfree_skb_any(skb);
+		if (pipe_id != USB_REG_IN_PIPE)
+			dev_kfree_skb_any(skb);
+		else
+			kfree_skb(skb);
 		return;
 	}
 
@@ -403,7 +406,7 @@
 			break;
 		}
 
-		dev_kfree_skb_any(skb);
+		kfree_skb(skb);
 
 	} else {
 		if (htc_hdr->flags & HTC_FLAGS_RECV_TRAILER)