A former Long Branch police officer was sentenced Friday to 10 years in state prison for running a methamphetamine lab out of his home and will be eligible for parole in two years, authorities said. Christopher Walls, 50, of Long Branch, previously lost his $128,000-a-year job and had to permanently surrender his guns and firearms ID card, the Monmouth County Prosecutor’s Office said. Walls pleaded pleaded guilty in November to causing a risk of widespread injury and manufacturing a controlled dangerous substance after being arrested last year. Cops saw materials and chemicals used to make met…