Re-enable proper gamma ramps with AMS

The huge gamma ramps from the atomic property that caused problems with Intel TigerLake hardware are apparently correct, we just had integer overflows in our calculations. By re-enabling this we get more accurate colors when a color profile is set, as the legacy gamma_size property is apparently always fixed at 256.

I'm not entirely sure if we're really getting overflows here / when compilers automatically increase the size of integers for calculations and such, but it's a possibility that it's what caused bug 440361.

Can someone with TigerLake hardware test?