first fruits - kill l2cap ->memcpy_fromiovec()

Just use copy_from_iter().  That's what this method is trying to do
in all cases, in a very convoluted fashion.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 5201d61..1754040 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -2096,8 +2096,7 @@
 	struct sk_buff **frag;
 	int sent = 0;
 
-	if (chan->ops->memcpy_fromiovec(chan, skb_put(skb, count),
-					msg, count))
+	if (copy_from_iter(skb_put(skb, count), count, &msg->msg_iter) != count)
 		return -EFAULT;
 
 	sent += count;
@@ -2117,8 +2116,8 @@
 
 		*frag = tmp;
 
-		if (chan->ops->memcpy_fromiovec(chan, skb_put(*frag, count),
-						msg, count))
+		if (copy_from_iter(skb_put(*frag, count), count,
+				   &msg->msg_iter) != count)
 			return -EFAULT;
 
 		sent += count;