[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/wireless/atmel.c b/drivers/net/wireless/atmel.c
index 1c17cbe..51a7db5 100644
--- a/drivers/net/wireless/atmel.c
+++ b/drivers/net/wireless/atmel.c
@@ -827,14 +827,14 @@
 	if (priv->wep_is_on)
 		frame_ctl |= IEEE80211_FCTL_PROTECTED;
 	if (priv->operating_mode == IW_MODE_ADHOC) {
-		memcpy(&header.addr1, skb->data, 6);
+		skb_copy_from_linear_data(skb, &header.addr1, 6);
 		memcpy(&header.addr2, dev->dev_addr, 6);
 		memcpy(&header.addr3, priv->BSSID, 6);
 	} else {
 		frame_ctl |= IEEE80211_FCTL_TODS;
 		memcpy(&header.addr1, priv->CurrentBSSID, 6);
 		memcpy(&header.addr2, dev->dev_addr, 6);
-		memcpy(&header.addr3, skb->data, 6);
+		skb_copy_from_linear_data(skb, &header.addr3, 6);
 	}
 
 	if (priv->use_wpa)