zink: remove depth_clip_control_missing workaround

The ANV bug this was meant to represent has been long fixed, and the
workaround has just been a proxy for EXT_depth_clip_control for a while
now.

Let's simplify things a bit, by removing this flag.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20740>

src/gallium/drivers/zink/zink_compiler.c

@@ -2865,7 +2865,7 @@ zink_shader_compile(struct zink_screen *screen, struct zink_shader *zs, nir_shad
             if (zs->sinfo.have_xfb)
                sinfo->last_vertex = true;
 
-            if (!zink_vs_key_base(key)->clip_halfz && screen->driver_workarounds.depth_clip_control_missing) {
+            if (!zink_vs_key_base(key)->clip_halfz && !screen->info.have_EXT_depth_clip_control) {
                NIR_PASS_V(nir, nir_lower_clip_halfz);
             }
             if (zink_vs_key_base(key)->push_drawid) {

src/gallium/drivers/zink/zink_pipeline.c

@@ -148,7 +148,7 @@ zink_create_gfx_pipeline(struct zink_screen *screen,
    viewport_state.pViewports = NULL;
    viewport_state.scissorCount = screen->info.have_EXT_extended_dynamic_state ? 0 : state->dyn_state1.num_viewports;
    viewport_state.pScissors = NULL;
-   if (!screen->driver_workarounds.depth_clip_control_missing && !hw_rast_state->clip_halfz)
+   if (screen->info.have_EXT_depth_clip_control && !hw_rast_state->clip_halfz)
       viewport_state.pNext = &clip;
 
    VkPipelineRasterizationStateCreateInfo rast_state = {0};

src/gallium/drivers/zink/zink_screen.c

@@ -2389,7 +2389,6 @@ init_driver_workarounds(struct zink_screen *screen)
                                                          screen->info.gpl_props.graphicsPipelineLibraryFastLinking ||
                                                          screen->is_cpu);
    screen->driver_workarounds.broken_l4a4 = screen->info.driver_props.driverID == VK_DRIVER_ID_NVIDIA_PROPRIETARY;
-   screen->driver_workarounds.depth_clip_control_missing = !screen->info.have_EXT_depth_clip_control;
    if (screen->info.driver_props.driverID == VK_DRIVER_ID_AMD_PROPRIETARY)
       /* this completely breaks xfb somehow */
       screen->info.have_EXT_extended_dynamic_state2 = false;

src/gallium/drivers/zink/zink_state.c

@@ -672,7 +672,7 @@ zink_bind_rasterizer_state(struct pipe_context *pctx, void *cso)
       ctx->rast_state_changed = true;
 
       if (clip_halfz != ctx->rast_state->base.clip_halfz) {
-         if (!screen->driver_workarounds.depth_clip_control_missing)
+         if (screen->info.have_EXT_depth_clip_control)
             ctx->gfx_pipeline_state.dirty = true;
          else
             zink_set_last_vertex_key(ctx)->clip_halfz = ctx->rast_state->base.clip_halfz;

src/gallium/drivers/zink/zink_types.h

@@ -1331,7 +1331,6 @@ struct zink_screen {
 
    struct {
       bool broken_l4a4;
-      bool depth_clip_control_missing;
       bool implicit_sync;
       bool always_feedback_loop;
       bool always_feedback_loop_zs;