system: Fix incorrect WatchdogTimer PATCH handler

Changes the incorrect WatchdogTimer property name to HostWatchdogTimer
in PATCH /redfish/v1/Systems/system handler to match the Redfish spec.

Tested:
Updating HostWatchdogTimer with PATCH request is handled properly.

Change-Id: Ic7c9c72e3fd43fb738f4fc21eb39e335aa8d1bcd
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@intel.com>
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index 32951ef..c1adc4c 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -3003,7 +3003,7 @@
                 if (!json_util::readJsonPatch(
                         req, asyncResp->res, "IndicatorLED", indicatorLed,
                         "LocationIndicatorActive", locationIndicatorActive,
-                        "Boot", bootProps, "WatchdogTimer", wdtTimerProps,
+                        "Boot", bootProps, "HostWatchdogTimer", wdtTimerProps,
                         "PowerRestorePolicy", powerRestorePolicy, "AssetTag",
                         assetTag, "PowerMode", powerMode, "IdlePowerSaver",
                         ipsProps))