[CFL] Change cfl_load to use width and height

Since the size used with cfl_load can either be based on the transform
block size and the prediction block size, width and height are used as
parameters instead of TX_SIZE.

This resolves a problem where cfl_compute_alpha_ind was reading
uninitialized memory.

Change-Id: I187dbdd5b2e8bd85e82bb77eb74859bee2cd3f1e