texture_cache: fix for unexpected scheduler flushes by detiler

src/video_core/buffer_cache/buffer.h

@@ -146,6 +146,10 @@ public:
         return offset;
     }
 
+    u64 GetFreeSize() const {
+        return size_bytes - offset - mapped_size;
+    }
+
 private:
     struct Watch {
         u64 tick{};

src/video_core/texture_cache/tile_manager.cpp

@@ -397,7 +397,7 @@ std::optional<vk::Buffer> TileManager::TryDetile(Image& image) {
     const u32 image_size = image.info.guest_size_bytes;
     const auto [in_buffer, in_offset] = [&] -> std::pair<vk::Buffer, u32> {
         // Use stream buffer for smaller textures.
-        if (image_size <= StreamBufferSize) {
+        if (image_size <= stream_buffer.GetFreeSize()) {
             u32 offset = stream_buffer.Copy(image.info.guest_address, image_size);
             return {stream_buffer.Handle(), offset};
         }