Change parameters for highbd tune=ssim

With this CL:
             PSNR   SSIM    MS-SSIM
lowres_10bd  2.8    -5.6    -6.5
midres_10bd  2.6    -5.6    -6.3

Before this CL:
             PSNR   SSIM    MS-SSIM
lowres_10bd  6.1    -6.5    -7.7
midres_10bd  6.2    -6.0    -7.2

Change-Id: Iad0ad96d55ad140db00ce86c34ab85461cd963eb
1 file changed