Add missing initializations of HBD buffers
Add missing initializations of HBD buffers

BUG=aomedia:530

Change-Id: I6889a9b7ba05785ea6d4c684e0e12dcc85fdca7c

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