decodeframe.c: simplify control flow
decodeframe.c: simplify control flow

Change-Id: I3faecc70004747a10cd51df9dbcb27b7c2d56703

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom