Change "mctp instance id" to "pldm instance id"

It's not a MCTP thing.

Change-Id: I922d28f848c8948d43ea4b8926d2310c8fb50228
Signed-off-by: Rashmica Gupta <rashmica@linux.ibm.com>
Signed-off-by: Lakshmi Yadlapati <lakshmiy@us.ibm.com>
diff --git a/pldm.hpp b/pldm.hpp
index 1f878e5..5d093a1 100644
--- a/pldm.hpp
+++ b/pldm.hpp
@@ -149,9 +149,9 @@
     void setTraceThrottle(const bool throttle);
 
   private:
-    /** @brief MCTP instance number used in PLDM requests
+    /** @brief PLDM instance number used in PLDM requests
      */
-    std::optional<uint8_t> mctpInstance;
+    std::optional<uint8_t> pldmInstanceID;
 
     /** @brief Callback handler to be invoked when the state of the OCC
      *         changes
@@ -307,7 +307,7 @@
      *
      * @return true if the id was found and false if not
      */
-    bool getMctpInstanceId();
+    bool getPldmInstanceId();
 
     /** @brief Encode a GetStateSensor command into a PLDM request
      *  @param[in] instance - OCC instance number