radv: Split submission in winsys instead of radv_queue.

radv: Split submission in winsys instead of radv_queue.

This will still make it so that RADV_DEBUG=hang will only submit
one command buffer at a time, but otherwise let's pass all CS
objects into one submission and let the winsys split them if
necessary.

The winsys can do a better job at splitting them because
radv_queue has no knowledge of IBs and ignores chaining in the
splitting logic.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22354>