[SK_BUFF]: Introduce skb_copy_to_linear_data{_offset}

To clearly state the intent of copying to 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@ghostprotocols.net>
diff --git a/drivers/net/irda/donauboe.c b/drivers/net/irda/donauboe.c
index 9987a0d..3ca47bf 100644
--- a/drivers/net/irda/donauboe.c
+++ b/drivers/net/irda/donauboe.c
@@ -1282,8 +1282,8 @@
                       skb_reserve (skb, 1);
 
                       skb_put (skb, len);
-                      memcpy (skb->data, self->rx_bufs[self->rxs], len);
-
+                      skb_copy_to_linear_data(skb, self->rx_bufs[self->rxs],
+					      len);
                       self->stats.rx_packets++;
                       skb->dev = self->netdev;
                       skb_reset_mac_header(skb);