[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/8139too.c b/drivers/net/8139too.c
index 2101334..a844b1f 100644
--- a/drivers/net/8139too.c
+++ b/drivers/net/8139too.c
@@ -1904,10 +1904,10 @@
 	u32 left = RX_BUF_LEN - offset;
 
 	if (size > left) {
-		memcpy(skb->data, ring + offset, left);
-		memcpy(skb->data+left, ring, size - left);
+		skb_copy_to_linear_data(skb, ring + offset, left);
+		skb_copy_to_linear_data_offset(skb, left, ring, size - left);
 	} else
-		memcpy(skb->data, ring + offset, size);
+		skb_copy_to_linear_data(skb, ring + offset, size);
 }
 #endif