Well, To get an earth power deino, you have to breed with a Garchomp with Earth power, now onto the system.
The pokemon you want to learn the move, must have it in its list of egg moves, and be a female.
Then you have to breed it with a male , in its egg group, who knows the desired move.
In your case.
Deino needs to know Earth Power, and is a Female.
Garchomp has access to the move, and is in the same egg group, so getting a male garchomp with earth power, is your answer.
Also, In case you didn't know, garchomp learns earth power via move tutor.