[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/rose/af_rose.c b/net/rose/af_rose.c
index f38c3b3..806bf6f 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -1181,7 +1181,7 @@
 
 			/* Duplicate the Header */
 			skb_push(skbn, ROSE_MIN_LEN);
-			memcpy(skbn->data, header, ROSE_MIN_LEN);
+			skb_copy_to_linear_data(skbn, header, ROSE_MIN_LEN);
 
 			if (skb->len > 0)
 				skbn->data[2] |= M_BIT;