lnwire: remove MaxPayloadLength from Message interface

Removes the MaxPayloadLength function from the Message interface
and checks that each message payload is not greater than MaxMsgBody.
Since all messages are now allowed to be 65535 bytes in size, the
MaxPayloadLength is no longer needed.

lnwire/update_fulfill_htlc.go

@@ -77,14 +77,6 @@ func (c *UpdateFulfillHTLC) MsgType() MessageType {
 	return MsgUpdateFulfillHTLC
 }
 
-// MaxPayloadLength returns the maximum allowed payload size for an UpdateFulfillHTLC
-// complete message observing the specified protocol version.
-//
-// This is part of the lnwire.Message interface.
-func (c *UpdateFulfillHTLC) MaxPayloadLength(uint32) uint32 {
-	return MaxMsgBody
-}
-
 // TargetChanID returns the channel id of the link for which this message is
 // intended.
 //