[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/net/netrom/nr_out.c b/net/netrom/nr_out.c
index 7c467c9..e3e6c44 100644
--- a/net/netrom/nr_out.c
+++ b/net/netrom/nr_out.c
@@ -59,8 +59,8 @@
 
 			/* Duplicate the Transport Header */
 			skb_push(skbn, NR_TRANSPORT_LEN);
-			memcpy(skbn->data, transport, NR_TRANSPORT_LEN);
-
+			skb_copy_to_linear_data(skbn, transport,
+						NR_TRANSPORT_LEN);
 			if (skb->len > 0)
 				skbn->data[4] |= NR_MORE_FLAG;