[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/irda/via-ircc.c b/drivers/net/irda/via-ircc.c
index 5ff4163..45bbd66 100644
--- a/drivers/net/irda/via-ircc.c
+++ b/drivers/net/irda/via-ircc.c
@@ -925,8 +925,8 @@
 
 	self->tx_fifo.tail += skb->len;
 	self->stats.tx_bytes += skb->len;
-	memcpy(self->tx_fifo.queue[self->tx_fifo.free].start, skb->data,
-	       skb->len);
+	skb_copy_from_linear_data(skb,
+		      self->tx_fifo.queue[self->tx_fifo.free].start, skb->len);
 	self->tx_fifo.len++;
 	self->tx_fifo.free++;
 //F01   if (self->tx_fifo.len == 1) {