[PATCH v2 0/2] module: expose imported namespaces via sysfs

Add /sys/module/*/import_ns to expose the symbol namespaces imported
by a loaded module.

Changes since v1:
- Simplified commit message to drop unnecessary/incorrect background
- Use .setup/.free callbacks in module_attribute to ensure
  imported_namespaces is NULL-initialized before error paths and
  NULL'd after kfree (Sami)
- Updated KernelVersion to 7.1 in docs for next merge window