radeonsi: don't use nir_io_dont_optimize because it's deprecated

There is a new environment variable that can be used instead.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32257>

src/gallium/drivers/radeonsi/si_debug_options.h

@@ -22,7 +22,6 @@ OPT_BOOL(dcc_msaa, true, "Enable DCC for MSAA for GFX10-10.3")
 OPT_BOOL(zerovram, false, "Zero all VRAM allocations")
 OPT_BOOL(clear_lds, false, "Clear LDS at the end of shaders. Might decrease performance.")
 OPT_BOOL(cache_rb_gl2, false, "Enable GL2 caching for CB and DB.")
-OPT_BOOL(optimize_io, true, "Run nir_opt_varyings in the GLSL linker.")
 
 #undef OPT_BOOL
 #undef OPT_INT

src/gallium/drivers/radeonsi/si_get.c

@@ -1576,8 +1576,7 @@ void si_init_screen_get_functions(struct si_screen *sscreen)
     * when execution mode is rtz instead of rtne.
     */
    options->force_f2f16_rtz = true;
-   options->io_options |= (!has_mediump ? nir_io_mediump_is_32bit : 0) | nir_io_has_intrinsics |
-                          (sscreen->options.optimize_io ? 0 : nir_io_dont_optimize);
+   options->io_options |= (!has_mediump ? nir_io_mediump_is_32bit : 0) | nir_io_has_intrinsics;
    options->lower_mediump_io = has_mediump ? si_lower_mediump_io : NULL;
    /* HW supports indirect indexing for: | Enabled in driver
     * -------------------------------------------------------

src/gallium/drivers/radeonsi/si_state_shaders.cpp

@@ -147,8 +147,7 @@ void si_get_ir_cache_key(struct si_shader_selector *sel, bool ngg, bool es,
    /* bit gap */
    if (wave_size == 32)
       shader_variant_flags |= 1 << 2;
-   if (sel->screen->options.optimize_io)
-      shader_variant_flags |= 1 << 3;
+   /* bit gap */
    /* use_ngg_culling disables NGG passthrough for non-culling shaders to reduce context
     * rolls, which can be changed with AMD_DEBUG=nonggc or AMD_DEBUG=nggc.
     */