Bitmask patch 6: Minor improvement.
Bitmask patch 6: Minor improvement.

Update bitmask to the exact bit, no need of for loop.

Change-Id: I8536e2b0511277df7944920d9e598edb60cebdef

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