radeonsi: enable nir_group_loads for better performance

radeonsi: enable nir_group_loads for better performance

The best case I have is one viewperf subtest getting +9% performance.

56979 shaders in 34726 tests
Totals:
SGPRS: 2667522 -> 2669178 (0.06 %)
VGPRS: 1543608 -> 1553472 (0.64 %)
Spilled SGPRs: 4090 -> 4100 (0.24 %)
Spilled VGPRs: 1600 -> 1791 (11.94 %)
Private memory VGPRs: 256 -> 256 (0.00 %)
Scratch size: 1872 -> 2076 (10.90 %) dwords per thread
Code Size: 59443980 -> 59479804 (0.06 %) bytes
Max Waves: 867280 -> 865634 (-0.19 %)

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
v2: No change in pixels but the hash changed.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13604>