[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/pxaficp_ir.c b/drivers/net/irda/pxaficp_ir.c
index b3e1107..fb196fd 100644
--- a/drivers/net/irda/pxaficp_ir.c
+++ b/drivers/net/irda/pxaficp_ir.c
@@ -386,7 +386,7 @@
 
 		/* Align IP header to 20 bytes  */
 		skb_reserve(skb, 1);
-		memcpy(skb->data, si->dma_rx_buff, len);
+		skb_copy_to_linear_data(skb, si->dma_rx_buff, len);
 		skb_put(skb, len);
 
 		/* Feed it to IrLAP  */