[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/pcmcia/axnet_cs.c b/drivers/net/pcmcia/axnet_cs.c
index fabbe95..808fae1 100644
--- a/drivers/net/pcmcia/axnet_cs.c
+++ b/drivers/net/pcmcia/axnet_cs.c
@@ -1136,7 +1136,7 @@
 		ei_block_output(dev, length, skb->data, output_page);
 	else {
 		memset(packet, 0, ETH_ZLEN);
-		memcpy(packet, skb->data, skb->len);
+		skb_copy_from_linear_data(skb, packet, skb->len);
 		ei_block_output(dev, length, packet, output_page);
 	}