Modify av1_coef_cost to reflect that EOB values are sent
with each non-zero coefficient, and modify chroma weight
to preserve original chroma balance.

AWCY, objective-1-fast, new_token+ec_adapt vs ec_multisymbol:

PSNR YCbCr:     -0.43%      -0.52%      -0.58%
PSNRHVS:        -0.81%
SSIM:           -0.73%
MSSSIM:         -0.93%
CIEDE2000:      -0.36%

This change:

PSNR YCbCr:     -0.15%      0.83%      0.77%
PSNRHVS:        -0.24%
SSIM:           -0.23%
MSSSIM:         -0.24%
CIEDE2000:       0.24%

Change-Id: I7f2dd9f3cd24bb64eb4131cba94dda466b9691b0