Avoid the use of uninitialized value in ActiveMap encoding route
Avoid the use of uninitialized value in ActiveMap encoding route

This commit resets the transform size to be the maximum possible
value. It avoids out-of-boundary writing when the ActiveMap is
turned on.

Change-Id: I8302dd9a5c9fffaea3edf9ad33f72aa111999737

GrokImageCompression/aom,mbebenita/aom,GrokImageCompression/aom,smarter/aom,smarter/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,GrokImageCompression/aom,luctrudeau/aom,mbebenita/aom,mbebenita/aom,mbebenita/aom,mbebenita/aom,luctrudeau/aom,mbebenita/aom,mbebenita/aom,smarter/aom,GrokImageCompression/aom,smarter/aom,mbebenita/aom,smarter/aom,luctrudeau/aom,mbebenita/aom,luctrudeau/aom,GrokImageCompression/aom