MEM: Clean-up of Functional/Virtual/TranslatingPort remnants

This patch cleans up forward declarations and a member-function
prototype that still referred to the old FunctionalPort, VirtualPort
and TranslatingPort. There is no change in functionality.

src/arch/power/vtophys.hh

@@ -40,7 +40,6 @@
 #include "arch/power/utility.hh"
 
 class ThreadContext;
-class FunctionalPort;
 
 namespace PowerISA {