wayland/frog color management: use a reference luminance of 203 nits for scRGB
80 nits is correct, but Windows doesn't do correct, and with the frog protocol we know we're getting the image from a game using Windows scRGB. 203 nits is what we use for PQ, so this will ensure that PQ and scRGB modes in games look roughly the same.
(cherry picked from commit fb695ba7)
Co-authored-by: Xaver Hugl xaver.hugl@gmail.com