lnwire: limit channel update reader

Fixes a bug where channel update data is read until the end of the stream
rather than stopping after the specified length. This is problematic
when failure message tlv data is present, because this data is interpreted
as channel update tlv data.

docs/release-notes/release-notes-0.16.0.md

@@ -184,6 +184,10 @@ certain large transactions](https://github.com/lightningnetwork/lnd/pull/7100).
 
 * [Prevent nil pointer dereference during funding manager 
   test](https://github.com/lightningnetwork/lnd/pull/7268)
+  
+* Fixed a [failure message parsing bug](https://github.com/lightningnetwork/lnd/pull/7262)
+  that caused additional failure message data to be interpreted as being part of
+  a channel update.
 
 ## `lncli`