control: Setup configured power on delay retrieval

A configured power on delay comes from either a compile time YAML
generated `_powerOnDelay` entry or from parsing a future manager JSON
configuration file.

Tested:
    No impact to YAML driven configurations
    An initial power on delay of zero when use of JSON enabled

Change-Id: If87260d1cb310a0c30698c47024127cd5e8a37e1
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/manager.cpp b/control/manager.cpp
index 9213fd7..ff8afef 100644
--- a/control/manager.cpp
+++ b/control/manager.cpp
@@ -135,13 +135,16 @@
     {
         z.second->setFullSpeed();
     }
-#ifndef CONTROL_USE_JSON
+#ifdef CONTROL_USE_JSON
+    auto delay = getPowerOnDelay(_bus);
+#else
     auto delay = _powerOnDelay;
+#endif
     while (delay > 0)
     {
         delay = sleep(delay);
     }
-#endif
+
     util::SDBusPlus::callMethod(_bus, SYSTEMD_SERVICE, SYSTEMD_OBJ_PATH,
                                 SYSTEMD_INTERFACE, "StartUnit",
                                 FAN_CONTROL_READY_TARGET, "replace");