Create subfunctions in vpd-tool to reuse

This commit aims in creating sub-functions in vpd-tool
fixSystemVPD implementation, so that the code can be reused in
future.

Test:
Tested that vpd-tool --fixSystemVPD option works as expected.

Signed-off-by: Priyanga Ramasamy <priyanga24@in.ibm.com>
Change-Id: I6885b5642492a85a7087055a4b1bcf65c857c3ba
diff --git a/vpd_tool_impl.hpp b/vpd_tool_impl.hpp
index 6e85888..fc9b225 100644
--- a/vpd_tool_impl.hpp
+++ b/vpd_tool_impl.hpp
@@ -166,6 +166,14 @@
      */
     void printFixSystemVPDOption(UserOption option);
 
+    /**
+     * @brief Get System VPD data stored in cache
+     *
+     * @param[in] svpdBusData - Map of system VPD record data.
+     */
+    void getSystemDataFromCache(
+        openpower::vpd::inventory::IntfPropMap& svpdBusData);
+
   public:
     /**
      * @brief Dump the complete inventory in JSON format