panfrost: Remove stale TODO

While the text here is still nominally accurate, we should be seeing so few
shader variants at this point that the locking contention isn't a big deal.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20906>

src/gallium/drivers/panfrost/pan_shader.c

@@ -319,9 +319,6 @@ panfrost_update_shader_variant(struct panfrost_context *ctx,
 
    ctx->prog[type] = compiled;
 
-   /* TODO: it would be more efficient to release the lock before
-    * compiling instead of after, but that can race if thread A compiles a
-    * variant while thread B searches for that same variant */
    simple_mtx_unlock(&uncompiled->lock);
 }