Fix assertion fail in av1_left/above_block_mode()
Fix assertion fail in av1_left/above_block_mode()

BUG=aomedia:1221

Change-Id: I2893ab3c6f5a2403512890ec4ea929abedb14421

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