I copyed this from Carnivals Website.

Do I need to pack my Hair Dryer?

A hair dryer is provided in the bathroom (Destiny, Triumph, Victory) or at the desk/vanity in the stateroom (Spirit, Pride, Legend, Conquest, Glory, Miracle, Valor). Hair dryers are not provided in the staterooms of all other ships.

I guess they dont have in Fantasy Class and Hoilday class ships so bring your own.