Port: Make getAddrRanges const

This patch makes getAddrRanges const throughout the code base. There
is no reason why it should not be, and making it const prevents adding
any unintentional side-effects.

src/dev/pciconfigall.hh

@@ -80,7 +80,7 @@ class PciConfigAll : public PioDevice
 
     virtual Tick write(PacketPtr pkt);
 
-    AddrRangeList getAddrRanges();
+    AddrRangeList getAddrRanges() const;
 
   private:
     Addr pioAddr;