[SK_BUFF]: Introduce skb_copy_from_linear_data{_offset}

To clearly state the intent of copying from 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@redhat.com>
diff --git a/drivers/net/lance.c b/drivers/net/lance.c
index 11cbcb9..0fe96c8 100644
--- a/drivers/net/lance.c
+++ b/drivers/net/lance.c
@@ -988,7 +988,7 @@
 		if (lance_debug > 5)
 			printk("%s: bouncing a high-memory packet (%#x).\n",
 				   dev->name, (u32)isa_virt_to_bus(skb->data));
-		memcpy(&lp->tx_bounce_buffs[entry], skb->data, skb->len);
+		skb_copy_from_linear_data(skb, &lp->tx_bounce_buffs[entry], skb->len);
 		lp->tx_ring[entry].base =
 			((u32)isa_virt_to_bus((lp->tx_bounce_buffs + entry)) & 0xffffff) | 0x83000000;
 		dev_kfree_skb(skb);