Bring 2 cups milk and broth to a simmer in a medium saucepan over medium heat. Gradually add polenta. Cook for 20 minutes or until thick and bubbly, stirring frequently with a whisk; remove from heat. Stir in cream cheese. Keep warm.
Place vinegar in a small saucepan over medium-high heat. Bring to a boil, and cook until reduced by half (about 5 minutes).
Place a grill pan over medium-high heat. Combine rosemary, salt, pepper, and garlic; rub mixture over pork. Place pork in pan; cook for 5 minutes on each side or until desired degree of doneness, basting with vinegar. Let stand 5 minutes before slicing. Serve with polenta.