[vulkan] Fix VUID-VkImageMemoryBarrier-synchronization2-07794

Since we don't use synchronization2, the said layout is wrong and must be VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL.
P.s. in future if we do use synchronization2, this change is compatible.

src/video_core/renderer_vulkan/blit_image.cpp

@@ -518,7 +518,7 @@ void BlitImageHelper::BlitColor(const Framebuffer* dst_framebuffer, VkImageView
     scheduler.RequestOutsideRenderPassOperationContext();
     scheduler.Record([this, dst_framebuffer, src_image_view, src_image, src_sampler, dst_region,
                       src_region, src_size, pipeline, layout](vk::CommandBuffer cmdbuf) {
-        TransitionImageLayout(cmdbuf, src_image, VK_IMAGE_LAYOUT_READ_ONLY_OPTIMAL);
+        TransitionImageLayout(cmdbuf, src_image,  VK_IMAGE_LAYOUT_GENERAL);
         BeginRenderPass(cmdbuf, dst_framebuffer);
         const VkDescriptorSet descriptor_set = one_texture_descriptor_allocator.Commit();
         UpdateOneTextureDescriptorSet(device, descriptor_set, src_sampler, src_image_view);