pldmtool/softoff: Use InstanceId APIs from libpldm

The af-mctp transport does not broadcast the PLDM messages between the
MCTP socket instances. Pldmtool/softoff have to handle get/free
instanceId instead of depending on the pldmd. Update pldmtool/softoff
to use get/free instanceId APIs in libpldm.

Tested.
1. Call more than 32 pldmtool commands to make sure the allocated
InstanceId are free correctly.
2. Repeat calling softoff more than 32 times. Make sure the functional
should work normally.

Signed-off-by: Dung Cao <dung@os.amperecomputing.com>
Signed-off-by: Thu Nguyen <thu@os.amperecomputing.com>
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Change-Id: I7cda124694d95d00c37f4993e22cfe33a980d364
diff --git a/pldmtool/pldm_cmd_helper.hpp b/pldmtool/pldm_cmd_helper.hpp
index 1f21ea2..2488135 100644
--- a/pldmtool/pldm_cmd_helper.hpp
+++ b/pldmtool/pldm_cmd_helper.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "common/instance_id.hpp"
 #include "common/utils.hpp"
 
 #include <err.h>
@@ -137,6 +138,7 @@
 
   protected:
     uint8_t instanceId;
+    pldm::InstanceIdDb instanceIdDb;
 };
 
 } // namespace helper