vk_compute_pass: Use VK_ACCESS_NONE

This enumeration was introduced in Vulkan 1.3, prefer using this instead of defaulting the enum.

Also resolves a narrowing conversion warning on MSVC.

src/video_core/renderer_vulkan/vk_compute_pass.cpp

@@ -333,7 +333,7 @@ void ASTCDecoderPass::Assemble(Image& image, const StagingBufferRef& map,
             const VkImageMemoryBarrier image_barrier{
                 .sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER,
                 .pNext = nullptr,
-                .srcAccessMask = is_initialized ? VK_ACCESS_SHADER_WRITE_BIT : VkAccessFlagBits{},
+                .srcAccessMask = is_initialized ? VK_ACCESS_SHADER_WRITE_BIT : VK_ACCESS_NONE,
                 .dstAccessMask = VK_ACCESS_SHADER_READ_BIT | VK_ACCESS_SHADER_WRITE_BIT,
                 .oldLayout = is_initialized ? VK_IMAGE_LAYOUT_GENERAL : VK_IMAGE_LAYOUT_UNDEFINED,
                 .newLayout = VK_IMAGE_LAYOUT_GENERAL,