Remove reference to undefined nmv_ctx
Remove reference to undefined nmv_ctx

This was causing an undeclared identifier error.

Change-Id: Ie050bbcd1ef493840122980f472d995fdfb8b668

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