zink: use helper function to handle uvec/bvec types

bit_size of 1 means we use a bool type here, 32 means uint, so we can just
handle that automatically for all relevant cases

ref shaders@glsl-vs-continue-in-switch-in-do-while

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5911>