radv/gfx10: fix required ballot size with VK_EXT_subgroup_size_control

radv/gfx10: fix required ballot size with VK_EXT_subgroup_size_control

If compute shaders require a specific subgroup size (ie. Wave32),
we have to use the correct ballot size.

Fixes dEQP-VK.subgroups.ballot_other.compute.*_requiredsubgroupSize.

Fixes: fb07fd4e6cb ("radv: implement VK_EXT_subgroup_size_control")
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4215>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4215>