Remove dead code from av1_dering_search.
Remove dead code from av1_dering_search.

Change-Id: I893914d4678372970680b514843da87a75c14889

shacklettbp/aom,shacklettbp/aom,smarter/aom,mbebenita/aom,mbebenita/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,mbebenita/aom,shacklettbp/aom,mbebenita/aom,luctrudeau/aom,luctrudeau/aom,GrokImageCompression/aom,mbebenita/aom,smarter/aom,shacklettbp/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,mbebenita/aom,mbebenita/aom,smarter/aom,shacklettbp/aom,smarter/aom,GrokImageCompression/aom,smarter/aom,mbebenita/aom,GrokImageCompression/aom,GrokImageCompression/aom,mbebenita/aom,luctrudeau/aom,shacklettbp/aom