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/6lowpan.c b/net/bluetooth/6lowpan.c
index d8c67a5e..76617be 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -541,7 +541,7 @@
 	iv.iov_len = skb->len;
 
 	memset(&msg, 0, sizeof(msg));
-	iov_iter_init(&msg.msg_iter, WRITE, (struct iovec *) &iv, 1, skb->len);
+	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, &iv, 1, skb->len);
 
 	err = l2cap_chan_send(chan, &msg, skb->len);
 	if (err > 0) {
@@ -1050,7 +1050,6 @@
 	.suspend		= chan_suspend_cb,
 	.get_sndtimeo		= chan_get_sndtimeo_cb,
 	.alloc_skb		= chan_alloc_skb_cb,
-	.memcpy_fromiovec	= l2cap_chan_no_memcpy_fromiovec,
 
 	.teardown		= l2cap_chan_no_teardown,
 	.defer			= l2cap_chan_no_defer,