use ZoneInterface pointers where Dbus aspect not important

The implementation of the ZoneInterface used is the DbusPidZone, however
using the ZoneInterface when the Dbus aspect is unimportant provides for
trivial support of other implementations.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I0ed87322904e7f87e5b5c8a50c01144f3d843a10
diff --git a/pid/builder.hpp b/pid/builder.hpp
index 4db7447..ff2f682 100644
--- a/pid/builder.hpp
+++ b/pid/builder.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
-#include "pid/zone.hpp"
+#include "conf.hpp"
+#include "pid/zone_interface.hpp"
 #include "sensors/manager.hpp"
 
 #include <sdbusplus/bus.hpp>
@@ -11,7 +12,7 @@
 namespace pid_control
 {
 
-std::unordered_map<int64_t, std::unique_ptr<DbusPidZone>>
+std::unordered_map<int64_t, std::unique_ptr<ZoneInterface>>
     buildZones(const std::map<int64_t, conf::PIDConf>& zonePids,
                std::map<int64_t, struct conf::ZoneConfig>& zoneConfigs,
                SensorManager& mgr, sdbusplus::bus::bus& modeControlBus);