Add a small clean up on the unified use of mbmi
Add a small clean up on the unified use of mbmi

Change-Id: I51a751cd656846e6f3db6c15e320bdc7f1c868fe

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