Remove dead members: y_mode_prob, uv_mode_prob
Remove dead members: y_mode_prob, uv_mode_prob

Change-Id: I5b03c02657134bbd50c647645898c5d2f6286d2a

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