Fix unsigned integer overflow warning in quantize_b_helper_c()
Fix unsigned integer overflow warning in quantize_b_helper_c()

Change-Id: Ida42485e3fd44d332d70cb57010a0add2436abfe

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