[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/w83977af_ir.c b/drivers/net/irda/w83977af_ir.c
index bee4451..0d4a686 100644
--- a/drivers/net/irda/w83977af_ir.c
+++ b/drivers/net/irda/w83977af_ir.c
@@ -529,7 +529,7 @@
 	/* Decide if we should use PIO or DMA transfer */
 	if (self->io.speed > PIO_MAX_SPEED) {
 		self->tx_buff.data = self->tx_buff.head;
-		memcpy(self->tx_buff.data, skb->data, skb->len);
+		skb_copy_from_linear_data(skb, self->tx_buff.data, skb->len);
 		self->tx_buff.len = skb->len;
 		
 		mtt = irda_get_mtt(skb);