Apple is accepting iPhone 6s and iPhone 6s Plus reservations in six of the 40 countries where the new phones are set to debut this Friday. Customers in Belgium, Italy, Spain, Sweden, Switzerland and the Netherlands can pick the model, color and storage size they want and reserve a phone for in-store pickup Friday, although iPhone 6s Plus models are still in limited supply at most locations. Reservations are limited to two per customer and valid government-issued…