You're never required to like anyone. Having said that, you say you're tired of trying but you may want to consider trying something different. Your husband's dad doesn't like your dad for whatever reason. But you are not your dad. Have you ever calmly sat with your father in law and asked him what it is about you specifically that he doesn't like? I use the word calmly because I suspect there has most likely been an edge on any conversations you may have had with him. And I'm not saying you're responsible for it if there has been.
Be yourself and try to see things from your father in law's perspective. That doesn't mean he's right but it will give you a little more insight into what he may be looking for from you. It may be that this is a situation that is not fixable. If not, move forward and work at not letting it become an issue between you and your husband.
Whatever happened between the two dads is between them. If they want to waste their energy not liking each other, that is their issue and doesn't have to be anyone else's.