venus: virtgpu: Require stable wire format

When VMMs do not support VIRTGPU_DRM_CAPSET_VENUS the capset data
remains zeroed. By requiring the stable wire_format_version 1 this can
be detected early without initialising the renderer.

Avoids triggering `assert(capset->supports_blob_id_0);` in debug builds
under such circumstances.

Cc: mesa-stable
Signed-off-by: Janne Grunau <j@jannau.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34613>
(cherry picked from commit 3d3ca9b65e2dc09a765aba3c0e4b3878bd0a83bc)

.pick_status.json

@@ -424,7 +424,7 @@
         "description": "venus: virtgpu: Require stable wire format",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": null,
         "notes": null

src/virtio/vulkan/vn_renderer_virtgpu.c

@@ -1490,6 +1490,14 @@ virtgpu_init_capset(struct virtgpu *gpu)
       return VK_ERROR_INITIALIZATION_FAILED;
    }
 
+   if (gpu->capset.data.wire_format_version == 0) {
+      if (VN_DEBUG(INIT)) {
+         vn_log(gpu->instance, "Unsupported wire format version %u",
+                gpu->capset.data.wire_format_version);
+      }
+      return VK_ERROR_INITIALIZATION_FAILED;
+   }
+
    return VK_SUCCESS;
 }