[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/atm/br2684.c b/net/atm/br2684.c
index a1686df..0e9f00c 100644
--- a/net/atm/br2684.c
+++ b/net/atm/br2684.c
@@ -173,7 +173,7 @@
 	}
 	skb_push(skb, minheadroom);
 	if (brvcc->encaps == e_llc)
-		memcpy(skb->data, llc_oui_pid_pad, 10);
+		skb_copy_to_linear_data(skb, llc_oui_pid_pad, 10);
 	else
 		memset(skb->data, 0, 2);
 #endif /* FASTER_VERSION */