add handler logic to handle SysEntityName

Add handler logic to handler for SysEntityName such that it splits the
true IPMI processing from the business logic.

Tested: Only ran unit-tests (added new ones).
Change-Id: I6d672a80f85843ff98c2c7e5daf4689932ff96f9
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/entity_name.hpp b/entity_name.hpp
index a1bc9f4..cf35e0d 100644
--- a/entity_name.hpp
+++ b/entity_name.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "handler.hpp"
+
 #include <ipmid/api.h>
 
 namespace google
@@ -10,7 +12,8 @@
 // Handle the "entity id:entity instance" to entity name mapping command.
 // Sys can query the entity name for a particular "entity id:entity instance".
 ipmi_ret_t GetEntityName(const uint8_t* reqBuf, uint8_t* replyBuf,
-                         size_t* dataLen);
+                         size_t* dataLen,
+                         HandlerInterface* handler = &handlerImpl);
 
 } // namespace ipmi
 } // namespace google