Dear Student,
Yes you can definitely register yourself for Bachelors of Mass Media and Mass Communication. You can apply being once you have completed your 12th your results are out or not doesn't matters in registration. You awaiting 12th result will be of no problem for applying and registering. But if later when results are out and if you are found to have failed your application will be rejected and you will be disqualified which in the best scenario would never happen. So, you should go and register yourself.
Hope this might help you.