brw: Delete input_slots_valid from brw_wm_prog_key

Nothing in the compiler seems to use this anymore.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38556>

src/gallium/drivers/iris/iris_program.c

@@ -582,7 +582,6 @@ iris_to_brw_fs_key(const struct iris_screen *screen,
       .force_dual_color_blend = key->force_dual_color_blend,
       .coherent_fb_fetch = key->coherent_fb_fetch,
       .color_outputs_valid = key->color_outputs_valid,
-      .input_slots_valid = key->input_slots_valid,
       .ignore_sample_mask_out = !key->multisample_fbo,
       .null_push_constant_tbimr_workaround =
          screen->devinfo->needs_null_push_constant_tbimr_workaround,

src/intel/compiler/brw/brw_compiler.h

@@ -401,8 +401,6 @@ struct brw_mesh_prog_key
 struct brw_wm_prog_key {
    struct brw_base_prog_key base;
 
-   uint64_t input_slots_valid;
-
    float min_sample_shading;
 
    uint8_t color_outputs_valid;

src/intel/compiler/brw/brw_debug_recompile.c

@@ -142,8 +142,6 @@ debug_fs_recompile(const struct brw_compiler *c, void *log,
    found |= check("ignore sample mask out", ignore_sample_mask_out);
    found |= check("coarse pixel", coarse_pixel);
 
-   found |= check("input slots valid", input_slots_valid);
-
    found |= debug_base_recompile(c, log, &old_key->base, &key->base);
 
    if (!found) {

src/intel/vulkan/anv_shader_compile.c

@@ -974,8 +974,6 @@ anv_shader_compile_fs(struct anv_device *device,
                        nir->info.separate_shader,
                        pos_slots);
 
-   shader_data->key.wm.input_slots_valid = prev_vue_map.slots_valid;
-
    struct brw_compile_fs_params params = {
       .base = {
          .nir = nir,