lp: change return of LpPacket::wireEncode() to non-const

refs #3324

Change-Id: I0b178bc59f8107a947f5f500d7db4cdb9c1e2596
diff --git a/src/lp/packet.cpp b/src/lp/packet.cpp
index c839666..8d62ed9 100644
--- a/src/lp/packet.cpp
+++ b/src/lp/packet.cpp
@@ -63,7 +63,7 @@
 template size_t
 Packet::wireEncode<encoding::EstimatorTag>(EncodingImpl<encoding::EstimatorTag>& encoder) const;
 
-const Block
+Block
 Packet::wireEncode() const
 {
   if (m_wire.hasWire()) {