OAKLAND, Calif. — When rest, rehab, a platelet-rich plasma injection and everything else he tried didn’t get his damaged left shoulder strong enough to return to the field, Tom Murphy was left with no other choice but the last option he wanted — surgery. Before Thursday’s game, manager Scott Servais announced that the veteran catcher has decided to undergo season-ending surgery to repair damage from tearing in the rotator cuff and labrum of his left shoulder. Murphy has been dealing with the left shoulder problems for the past few seasons. He’s had the shoulder dislocate either completely or p…