[vk] Fix dynamic vertex input state handling

Previously, UpdateVertexInput() was always called when
has_dynamic_vertex_input was true, even if the current graphics pipeline
was not created with VK_DYNAMIC_STATE_VERTEX_INPUT_EXT. This could lead
to unnecessary or invalid state updates.

This change:
- Adds GraphicsPipeline::HasDynamicVertexInput() to check whether the
  pipeline was created with dynamic vertex input enabled.
- Calls UpdateVertexInput() only when the current pipeline supports
  VK_DYNAMIC_STATE_VERTEX_INPUT_EXT.

This ensures vertex input state updates are applied only when valid,
improving correctness and preventing redundant updates.

src/video_core/renderer_vulkan/vk_graphics_pipeline.h

@@ -80,7 +80,8 @@ public:
         PipelineStatistics* pipeline_statistics, RenderPassCache& render_pass_cache,
         const GraphicsPipelineCacheKey& key, std::array<vk::ShaderModule, NUM_STAGES> stages,
         const std::array<const Shader::Info*, NUM_STAGES>& infos);
-
+    // True if this pipeline was created with VK_DYNAMIC_STATE_VERTEX_INPUT_EXT
+    bool HasDynamicVertexInput() const noexcept { return key.state.dynamic_vertex_input; }
     GraphicsPipeline& operator=(GraphicsPipeline&&) noexcept = delete;
     GraphicsPipeline(GraphicsPipeline&&) noexcept = delete;
 

src/video_core/renderer_vulkan/vk_rasterizer.cpp

@@ -1002,7 +1002,10 @@ void RasterizerVulkan::UpdateDynamicStates() {
         }
     }
     if (features.has_dynamic_vertex_input) {
-        UpdateVertexInput(regs);
+        if (auto* gp = pipeline_cache.CurrentGraphicsPipeline();
+                gp && gp->HasDynamicVertexInput()) {
+            UpdateVertexInput(regs);
+        }
     }
 }