Provide a way for rdci to get component version

For rdci, the version information of some components(such as RDCD),
cannot be obtained through the rdc_device_get_component_version API.

Here create a fake rdc API to get them.

Change-Id: I75d8bcd1993873cff209995b58362f75787a4598
Signed-off-by: Chen Gong <curry.gong@amd.com>

protos/rdc.proto

@@ -151,6 +151,9 @@ service RdcAPI {
   //    size_t config_size,
   //    rdc_diag_test_result_t* result);
   rpc DiagnosticTestCaseRun(DiagnosticTestCaseRunRequest) returns (DiagnosticTestCaseRunResponse) {}
+
+  //Just an RPC method not used as an API
+  rpc GetMixedComponentVersion(GetMixedComponentVersionRequest) returns (GetMixedComponentVersionResponse) {}
 }
 
 message Empty {
@@ -474,3 +477,12 @@ message DiagnosticTestCaseRunResponse {
   uint32 status = 1;
   DiagnosticTestResult result = 2;
 }
+
+message GetMixedComponentVersionRequest {
+  uint32 component_id = 1;
+}
+
+message GetMixedComponentVersionResponse {
+  uint32 status = 1;
+  string version = 2;
+}