Revert "[dxvk] Increase memory chunk size to 32 MiB"

This reverts commit 83ae39f.

Does not show any considerable advantage over the 16 MiB chunk size
and reduces the effectiveness of the host-visible device-local memory
type on AMD cards.

src/dxvk/dxvk_memory.h

@@ -251,7 +251,7 @@ namespace dxvk {
 
   private:
 
-    constexpr static VkDeviceSize ChunkSize = 32 * 1024 * 1024;
+    constexpr static VkDeviceSize ChunkSize = 16 * 1024 * 1024;
 
     const Rc<vk::DeviceFn>                 m_vkd;
     const VkPhysicalDeviceProperties       m_devProps;