[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/a2065.c b/drivers/net/a2065.c
index b38fc65..1226cbb 100644
--- a/drivers/net/a2065.c
+++ b/drivers/net/a2065.c
@@ -598,7 +598,7 @@
 	ib->btx_ring [entry].length = (-len) | 0xf000;
 	ib->btx_ring [entry].misc = 0;
 
-	memcpy ((char *)&ib->tx_buf [entry][0], skb->data, skblen);
+	skb_copy_from_linear_data(skb, &ib->tx_buf [entry][0], skblen);
 
 	/* Clear the slack of the packet, do I need this? */
 	if (len != skblen)