brcmfmac: Use __skb_peek().

Instead of direct SKB list pointer accesses.

In these situations, we absolutely know that the SKB queue in question
is non-empty.
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/bcmsdh.c

@@ -576,7 +576,7 @@ int brcmf_sdiod_recv_chain(struct brcmf_sdio_dev *sdiodev,
 
 	if (pktq->qlen == 1)
 		err = brcmf_sdiod_skbuff_read(sdiodev, sdiodev->func2, addr,
-					      pktq->next);
+					      __skb_peek(pktq));
 	else if (!sdiodev->sg_support) {
 		glom_skb = brcmu_pkt_buf_get_skb(totlen);
 		if (!glom_skb)

drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c

@@ -2189,7 +2189,7 @@ brcmf_sdio_txpkt_prep(struct brcmf_sdio *bus, struct sk_buff_head *pktq,
 	 * length of the chain (including padding)
 	 */
 	if (bus->txglom)
-		brcmf_sdio_update_hwhdr(pktq->next->data, total_len);
+		brcmf_sdio_update_hwhdr(__skb_peek(pktq)->data, total_len);
 	return 0;
 }