intel/fs: fix total_scratch computation

We only have a single prog_data::total_scratch for all shader variants (SIMD 8, 16, 32). Therefore we should always max the total_scratch on top of existing variant.

We probably haven't run into that issue before because we compile by increasing SIMD size and higher SIMD size is more likely to spill. But for bindless shaders with return shaders, if the last return part doesn't spill, we completely ignore the previous parts' scratch computation.

Signed-off-by: Lionel Landwerlin lionel.g.landwerlin@intel.com Cc: mesa-stable