Use MAX_ENTROPY_TOKENS and ENTROPY_NODES more consistently

There were many instances in the code of vp8_coef_tokens and
vp8_coef_tokens-1, which was a preprocessor macro despite the naming
convention. Replace these with MAX_ENTROPY_TOKENS and ENTROPY_NODES,
respectively.

Change-Id: I72c4f6c7634c94e1fa066cd511471e5592c748da
13 files changed