[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/ipw2100.c b/drivers/net/wireless/ipw2100.c
index ad6e4a4..9137a4d 100644
--- a/drivers/net/wireless/ipw2100.c
+++ b/drivers/net/wireless/ipw2100.c
@@ -2416,8 +2416,9 @@
 #ifdef IPW2100_RX_DEBUG
 	/* Make a copy of the frame so we can dump it to the logs if
 	 * ieee80211_rx fails */
-	memcpy(packet_data, packet->skb->data,
-	       min_t(u32, status->frame_size, IPW_RX_NIC_BUFFER_LENGTH));
+	skb_copy_from_linear_data(packet->skb, packet_data,
+				  min_t(u32, status->frame_size,
+					     IPW_RX_NIC_BUFFER_LENGTH));
 #endif
 
 	if (!ieee80211_rx(priv->ieee, packet->skb, stats)) {