cosmetic: clean encoder txb code
cosmetic: clean encoder txb code

Change-Id: I899cbbfe28a6d6e8718e18ecff310fe960c3f9bc

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