[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/bluetooth/dtl1_cs.c b/drivers/bluetooth/dtl1_cs.c
index 459aa97..7f9c54b 100644
--- a/drivers/bluetooth/dtl1_cs.c
+++ b/drivers/bluetooth/dtl1_cs.c
@@ -425,7 +425,7 @@
 		return -ENOMEM;
 
 	skb_reserve(s, NSHL);
-	memcpy(skb_put(s, skb->len), skb->data, skb->len);
+	skb_copy_from_linear_data(skb, skb_put(s, skb->len), skb->len);
 	if (skb->len & 0x0001)
 		*skb_put(s, 1) = 0;	/* PAD */