Implement the code related to the GetMixedComponentVersion()

Change-Id: I98aad97b4cb6498b7f2fc03a2d5ee7c9e949d5f1
Signed-off-by: Chen Gong <curry.gong@amd.com>

include/rdc_lib/impl/RdcEmbeddedHandler.h

@@ -91,6 +91,10 @@ class RdcEmbeddedHandler final : public RdcHandler {
   // Control API
   rdc_status_t rdc_field_update_all(uint32_t wait_for_update) override;
 
+  // It is just a client interface under the GRPC framework and is not used as an RDC API.
+  // Pure virtual functions need to be overridden.
+  rdc_status_t get_mixed_component_version(mixed_component_t component, mixed_component_version_t* p_mixed_compv) override;
+
   explicit RdcEmbeddedHandler(rdc_operation_mode_t op_mode);
   ~RdcEmbeddedHandler() final;