Change the signature of the command handler functions.

Resolves openbmc/openbmc#857

Change-Id: I0b7ca6665dd89629838a238d77aff67fec1818c7
Signed-off-by: Tom Joseph <tomjoseph@in.ibm.com>
diff --git a/command/sol_cmds.cpp b/command/sol_cmds.cpp
index 3096d2e..344b6d8 100644
--- a/command/sol_cmds.cpp
+++ b/command/sol_cmds.cpp
@@ -12,11 +12,10 @@
 
 using namespace phosphor::logging;
 
-std::vector<uint8_t> payloadHandler(std::vector<uint8_t>& inPayload,
+std::vector<uint8_t> payloadHandler(const std::vector<uint8_t>& inPayload,
                                     const message::Handler& handler)
 {
-    auto request = reinterpret_cast<Payload*>(inPayload.data());
-
+    auto request = reinterpret_cast<const Payload*>(inPayload.data());
     auto solDataSize = inPayload.size() - sizeof(Payload);
 
     Buffer charData(solDataSize);