Changed condition for using RD in Intra Mode

The condition for using RD when selecting the intra coding mode
for a MB is that the RD flag is set AND we're not in real-time
mode.

Previously the code used RD if either the RD flag was set OR
we were not using real-time mode.

Change-Id: Ic711151298468a3f99babad39ba8375f66d55a08