radeonsi: do VGT_FLUSH when switching NGG -> legacy on Sienna Cichlid

Other chips don't need this.

Fixes: 9538b9a68ed - radeonsi: add support for Sienna Cichlid

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7542>
(cherry picked from commit c4ebdf9ee7eac7241b5185d7d496e96384a41ecb)
diff --git a/.pick_status.json b/.pick_status.json
index 5c9ab07..7cd032c 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -706,7 +706,7 @@
         "description": "radeonsi: do VGT_FLUSH when switching NGG -> legacy on Sienna Cichlid",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "9538b9a68ed9aa0f8a231d6bf681f6f0a2a9d341"
     },