[VMA] Use Host cached and Host coherent for Download operations (#482)

Increase read speeds by using appropriate usage flags

Reviewed-on: #482
Reviewed-by: crueter <crueter@eden-emu.dev>
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>
Co-authored-by: wildcard <wildcard@eden-emu.dev>
Co-committed-by: wildcard <wildcard@eden-emu.dev>

src/video_core/vulkan_common/vulkan_memory_allocator.cpp

@@ -49,6 +49,9 @@ namespace Vulkan {
         }
 
         [[nodiscard]] VkMemoryPropertyFlags MemoryUsagePreferredVmaFlags(MemoryUsage usage) {
+            if (usage == MemoryUsage::Download) {
+                return VK_MEMORY_PROPERTY_HOST_CACHED_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT;
+            }
             return usage != MemoryUsage::DeviceLocal ? VK_MEMORY_PROPERTY_HOST_COHERENT_BIT
                                                      : VkMemoryPropertyFlagBits{};
         }