Refactor tx_size to pixel number in decodeframe.c
Refactor tx_size to pixel number in decodeframe.c

Use the table access to retrieve pixel numbers from tx_size.

Change-Id: Ibf392dcfdf80606b6ab972d60550ed75cbe652db

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