radeonsi: don't lower constant arrays to uniforms in GLSL IR

radeonsi: don't lower constant arrays to uniforms in GLSL IR

This re-enables the change made in 2f5783bc2b82 which was
incorrectly disabled by 3e1dd99adca5.

For radeonsi, we will prefer the NIR pass as it'll generate better code
(some index calculation and a single load vs. a load, then index
calculation, then another load) and oftentimes NIR optimization can kick
in and make all the access indices constant.

Fixes: 3e1dd99adca5 ("radeonsi: Remove a bunch of default handling of pipe caps.")
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4474>