linux-yocto/5.15: libbpf: Fix build warning on ref_ctr_off

Integrating the following commit(s) to linux-yocto/5.15:

    da5513f30187 libbpf: Fix build warning on ref_ctr_off

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit eb75d561)
Signed-off-by: Steve Sakoman <steve@sakoman.com>