nvk: Stop doubling root descriptors

Reviewed-by: Lorenzo Rossi <snowycoder@gmail.com>
Acked-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Mel Henning <mhenning@darkrefraction.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30403>

src/nouveau/vulkan/nvk_shader.c

@@ -403,15 +403,10 @@ nvk_lower_nir(struct nvk_device *dev, nir_shader *nir,
       /* Large constant support assumes cbufs */
       NIR_PASS(_, nir, nir_opt_large_constants, NULL, 32);
    } else {
-      /* Codegen sometimes puts stuff in cbuf 1 and adds 1 to our cbuf indices
-       * so we can't really rely on it for lowering to cbufs and instead place
-       * the root descriptors in both cbuf 0 and cbuf 1.
-       */
       *cbuf_map_out = (struct nvk_cbuf_map) {
-         .cbuf_count = 2,
+         .cbuf_count = 1,
          .cbufs = {
             { .type = NVK_CBUF_TYPE_ROOT_DESC },
-            { .type = NVK_CBUF_TYPE_ROOT_DESC },
          }
       };
    }