[D3D12] Treat gamma/as_16 EDRAM formats the same as their base formats

src/xenia/gpu/d3d12/texture_cache.h

@@ -142,7 +142,8 @@ class TextureCache {
     TileMode tile_mode;
     // Uncompression info for when the regular host format for this texture is
     // block-compressed, but the size is not block-aligned, and thus such
-    // texture cannot be created in Direct3D on PC and needs decompression.
+    // texture cannot be created in Direct3D on PC and needs decompression,
+    // however, such textures are common, for instance, in Halo 3.
     DXGI_FORMAT dxgi_format_uncompressed;
     LoadMode decompress_mode;
   };