PEL: Common function to call host iface response

Add a function to the HostInterface class to invoke the user defined
command response function if there is one, and then change the code to
use this new function.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: Ia376923df70863bcd46120cf23918c2f255f984f
diff --git a/test/openpower-pels/mocks.hpp b/test/openpower-pels/mocks.hpp
index 2457c0e..5781233 100644
--- a/test/openpower-pels/mocks.hpp
+++ b/test/openpower-pels/mocks.hpp
@@ -214,10 +214,7 @@
             status = ResponseStatus::failure;
         }
 
-        if (_responseFunc)
-        {
-            (*_responseFunc)(status);
-        }
+        callResponseFunc(status);
 
         // Keep account of the number of commands responses for testing.
         _cmdsProcessed++;