agx: Implement txd

Handles all cases except for cube maps, which don't seem to work
properly, so those are lowered.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18525>

src/asahi/compiler/agx_compiler.h

@@ -256,8 +256,8 @@ enum agx_lod_mode {
    AGX_LOD_MODE_AUTO_LOD = 0,
    AGX_LOD_MODE_AUTO_LOD_BIAS = 5,
    AGX_LOD_MODE_LOD_MIN = 6,
-   AGX_LOD_GRAD = 8,
-   AGX_LOD_GRAD_MIN = 12
+   AGX_LOD_MODE_LOD_GRAD = 4,
+   AGX_LOD_MODE_LOD_GRAD_MIN = 12
 };
 
 enum agx_dim {