[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>

drivers/net/e1000/e1000_main.c

@@ -4224,9 +4224,12 @@ e1000_clean_rx_irq(struct e1000_adapter *adapter,
 			    netdev_alloc_skb(netdev, length + NET_IP_ALIGN);
 			if (new_skb) {
 				skb_reserve(new_skb, NET_IP_ALIGN);
-				memcpy(new_skb->data - NET_IP_ALIGN,
-				       skb->data - NET_IP_ALIGN,
-				       length + NET_IP_ALIGN);
+				skb_copy_to_linear_data_offset(new_skb,
+							       -NET_IP_ALIGN,
+							       (skb->data -
+							        NET_IP_ALIGN),
+							       (length +
+							        NET_IP_ALIGN));
 				/* save the skb in buffer_info as good */
 				buffer_info->skb = skb;
 				skb = new_skb;