Unify block partition context and update functions between enc/dec
Unify block partition context and update functions between enc/dec

Remove the decoder side implementation. Use the common functions
for both encoder and decoder.

Change-Id: Idcb4deedd6d2de5476b7f2e7e907fd4a7761fafa

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