Il Mulino’s new uptown location has stars scrambling for reservations. Spies say Jon Bon Jovi and five pals were spotted at the restaurant Wednesday enjoying buffalo mozzarella, langoustines and whole branzino. On the same night, “Real Housewives” star Ramona Singer — who recently launched her own Ramona red wine, a Sangiovese Merlot blend — arrived looking for a reservation for the following night. But a source says, “When Ramona was told that she couldn’t be accommodated, she left in a huff.” Castmate Sonja Morgan, however, showed up without a booking and cheerfully took a seat at the bar.