[SK_BUFF]: Introduce skb_copy_from_linear_data{_offset}

To clearly state the intent of copying from linear sk_buffs, _offset being a
overly long variant but interesting for the sake of saving some bytes.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/drivers/char/pcmcia/synclink_cs.c b/drivers/char/pcmcia/synclink_cs.c
index 8d025e9..157b1d0 100644
--- a/drivers/char/pcmcia/synclink_cs.c
+++ b/drivers/char/pcmcia/synclink_cs.c
@@ -4169,7 +4169,7 @@
 	netif_stop_queue(dev);
 
 	/* copy data to device buffers */
-	memcpy(info->tx_buf, skb->data, skb->len);
+	skb_copy_from_linear_data(skb, info->tx_buf, skb->len);
 	info->tx_get = 0;
 	info->tx_put = info->tx_count = skb->len;