For mono set filmgrain chroma_scaling_from_luma=0
For mono set filmgrain chroma_scaling_from_luma=0

BUG=aomedia:1820

Change-Id: Ibb65ae90dea3e1c3ec29ed987f2adfd5075a6683

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