Apply suggestions from code review

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

Author: hasty

src/app/clusters/thermostat-server/thermostat-server.cpp

@@ -1403,7 +1403,7 @@ bool handleAtomicBegin(chip::app::CommandHandler * commandObj, const chip::app::
     uint16_t maxTimeout = 5000;
     timeout             = std::min(timeout, maxTimeout);
 
-    ScheduleTimer(endpoint, static_cast<System::Clock::Milliseconds16>(timeout));
+    ScheduleTimer(endpoint, System::Clock::Milliseconds16(timeout));
     gThermostatAttrAccess.SetAtomicWrite(endpoint, true);
     gThermostatAttrAccess.SetAtomicWriteScopedNodeId(endpoint, GetSourceScopedNodeId(commandObj));
     Commands::AtomicResponse::Type response;