freedreno: Share consts between different stages properly

Ever since a3xx, the const file has been shared between the different stages in the pipeline. Recently with a6xx, it was partitioned into VS & FS halves, but there's still a combined limit. However we never handled this correctly, leaving the possibility of hangs if all stages combined use more than the total limit. This series fixes that for a6xx, although a3xx-a5xx need a bigger rework to use ir3_cache, and a3xx also needs to program the const file offset registers correctly.

This fixes dEQP-VK.ubo.random.all_out_of_order_offsets.45 on turnip, which was the last CTS test hanging on a640.