now we're reaching. He didn't visit him because he missed manipulating him. There have been many a times throughout the series where we see examples of a connection they share, including Walt referring to his own son as Jesse, among more.
He visited him because there's something there, he mentions it, they been through a lot together, shared ridiculous moments in pivotal moments in both their lives. That's something you don't forget just because you're crazy ol' heisenberg. A theme throughout the episode was Walt taking stock of his own life, and clearly because of the visit and the money he leaves him, he is acknowledging him in a positive way, despite all the bad blood.