STYLE: simplify return statement

src/OpenFOAM/db/Time/Time.C

@@ -952,7 +952,7 @@ bool Foam::Time::stopAt(const stopAtControls stopCtrl) const
 
 bool Foam::Time::isAdjustTimeStep() const
 {
-    return controlDict_.lookupOrDefault("adjustTimeStep", false) ? true : false;
+    return controlDict_.lookupOrDefault("adjustTimeStep", false);
 }