During a game a defender, facing his own goal attempts to pass the ball back to his own goalkeeper.

He over hits the pass and the ball now heads towards his own goal

The goalkeeper takes two steps backwards and makes a save, punching the ball over the goal line.

What's your call?

The referee should award an indirect free kick against the goalkeeper's team from the place where he touched the ball with his hands, subject to the special circumstances of Law 8. 

No cards need to be issued.

In this situation, the goalkeeper infringes Law 12 at the moment he touches the ball with his hands after it has been deliberately kicked to him by his teammate. After that, everything else is irrelevant. 

If you award a corner kick, you are bypassing the Law.

Some thought the goalkeeper should be sent off because he denied the opposing team a goal or an obvious goal scoring opportunity by an offense punishable by a free kick. 

For these individuals, I refer your attention to Law 12 Sending off Offenses #4. that specifically states that denying a goal or an obvious goal scoring opportunity by deliberately handling the ball does not apply to a goalkeeper within his own penalty area. So, in this situation, a send off is not in order.