[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/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index 166c959..3666586 100644
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -661,7 +661,7 @@
 
 	if (skb) {
 		__skb_put(skb, IMMED_PKT_SIZE);
-		memcpy(skb->data, resp->imm_data, IMMED_PKT_SIZE);
+		skb_copy_to_linear_data(skb, resp->imm_data, IMMED_PKT_SIZE);
 	}
 	return skb;
 }
@@ -1722,11 +1722,11 @@
 {
 	skb->len = len;
 	if (len <= SKB_DATA_SIZE) {
-		memcpy(skb->data, p->va, len);
+		skb_copy_to_linear_data(skb, p->va, len);
 		skb->tail += len;
 		put_page(p->frag.page);
 	} else {
-		memcpy(skb->data, p->va, SKB_DATA_SIZE);
+		skb_copy_to_linear_data(skb, p->va, SKB_DATA_SIZE);
 		skb_shinfo(skb)->frags[0].page = p->frag.page;
 		skb_shinfo(skb)->frags[0].page_offset =
 		    p->frag.page_offset + SKB_DATA_SIZE;