radv: Fix various non-critical integer overflows

radv: Fix various non-critical integer overflows

The result of 0xf << 28 is a signed integer and hence overflows into the sign
bit. In practice compilers did the right thing here, since the intent of the
code was unsigned arithmetic anyway.

These conditions were observed in:
* dEQP-VK.pipeline.image.suballocation.sampling_type.combined.view_type.1d.format.r4g4b4a4_unorm_pack16.count_8.size.512x1
* dEQP-VK.binding_model.descriptorset_random.sets32.noarray.ubolimitlow.sbolimitlow.sampledimglow.outimgonly.noiub.nouab.frag.ialimithigh.0

Cc: mesa-stable
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6568>