net: mdio: use macro __ATTRIBUTE_GROUPS Use macro __ATTRIBUTE_GROUPS() to simplify the code. Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> Link: https://patch.msgid.link/260fb184-c662-415c-b288-e1423097f2b9@gmail.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>