[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/arch/ia64/sn/kernel/xpnet.c b/arch/ia64/sn/kernel/xpnet.c
index 9fc0265..5419acb 100644
--- a/arch/ia64/sn/kernel/xpnet.c
+++ b/arch/ia64/sn/kernel/xpnet.c
@@ -233,7 +233,7 @@
 			"%lu)\n", skb->data, &msg->data,
 			(size_t) msg->embedded_bytes);
 
-		memcpy(skb->data, &msg->data, (size_t) msg->embedded_bytes);
+		skb_copy_to_linear_data(skb, &msg->data, (size_t)msg->embedded_bytes);
 	} else {
 		dev_dbg(xpnet, "transferring buffer to the skb->data area;\n\t"
 			"bte_copy(0x%p, 0x%p, %hu)\n", (void *)msg->buf_pa,