fixed bug introduced last week when TDD config 3 is used. RA was never...

fixed bug introduced last week when TDD config 3 is used.  RA was never scheduled (commented out in openair2/LAYER2/MAC/eNB_scheduler.c)

git-svn-id: http://svn.eurecom.fr/openair4G/trunk@6718 818b1a75-f10b-46b9-bf7c-635c3b92a50f