[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/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 162eab6..a586787 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -2107,7 +2107,8 @@
 		if (!(conn->rx_skb = bt_skb_alloc(len, GFP_ATOMIC)))
 			goto drop;
 
-		memcpy(skb_put(conn->rx_skb, skb->len), skb->data, skb->len);
+		skb_copy_from_linear_data(skb, skb_put(conn->rx_skb, skb->len),
+			      skb->len);
 		conn->rx_len = len - skb->len;
 	} else {
 		BT_DBG("Cont: frag len %d (expecting %d)", skb->len, conn->rx_len);
@@ -2128,7 +2129,8 @@
 			goto drop;
 		}
 
-		memcpy(skb_put(conn->rx_skb, skb->len), skb->data, skb->len);
+		skb_copy_from_linear_data(skb, skb_put(conn->rx_skb, skb->len),
+			      skb->len);
 		conn->rx_len -= skb->len;
 
 		if (!conn->rx_len) {