Fix datetime options bug

Author: catamorphism

icu4c/source/i18n/messageformat2_function_registry.cpp

@@ -870,7 +870,7 @@ StandardFunctions::DateTimeValue::DateTimeValue(DateTimeFactory::DateTimeType ty
     UnicodeString dateStyleOption = opts.getStringFunctionOption(dateStyleName);
     UnicodeString timeStyleOption = opts.getStringFunctionOption(timeStyleName);
     bool hasDateStyleOption = dateStyleOption.length() > 0;
-    bool hasTimeStyleOption = dateStyleOption.length() > 0;
+    bool hasTimeStyleOption = timeStyleOption.length() > 0;
     bool noOptions = opts.optionsCount() == 0;
 
     using DateTimeType = DateTimeFactory::DateTimeType;