Small fixes for net ipmi handler

Host ipmid handler will not re-register commands,
so make the net handler follow this by skipping later registrations.
Also pass size of command to handlers for length checks to work.
Host ipmi handler passes this parameter correctly.

Change-Id: I8eb1d645eff405b91e471433085025b6835f0bd2
Signed-off-by: Feist, James <james.feist@linux.intel.com>
diff --git a/command_table.hpp b/command_table.hpp
index 62738c8..7d2fe13 100644
--- a/command_table.hpp
+++ b/command_table.hpp
@@ -269,8 +269,8 @@
          *
          * @return: None
          *
-         * @note Registering an already registered command will overwrite the
-         *       existing entry with the new one.
+         * @note: Duplicate registrations will be rejected.
+         *
          */
         void registerCommand(CommandID inCommand,
                              std::unique_ptr<Entry>&& entry);