Revert "hidl-gen: virtual inheritance from super interface"

This reverts commit ab281a7238dbed89bb078fd5baf75df429b0a7f7.

Change-Id: I5e8abf7c05614c222c0fb273700957cb840ee797
diff --git a/generateCpp.cpp b/generateCpp.cpp
index 921d6ae..8e63349 100644
--- a/generateCpp.cpp
+++ b/generateCpp.cpp
@@ -171,7 +171,7 @@
         if (superType == NULL) {
             out << " : virtual public IHidlInterfaceBase";
         } else {
-            out << " : virtual public "
+            out << " : public "
                 << superType->fullName();
         }