[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/appletalk/ltpc.c b/drivers/net/appletalk/ltpc.c
index 43c17c8..6a6cbd3 100644
--- a/drivers/net/appletalk/ltpc.c
+++ b/drivers/net/appletalk/ltpc.c
@@ -774,7 +774,7 @@
 	skb_pull(skb,3);
 
 	/* copy ddp(s,e)hdr + contents */
-	memcpy(skb->data,(void*)ltdmabuf,len);
+	skb_copy_to_linear_data(skb, ltdmabuf, len);
 
 	skb_reset_transport_header(skb);