bpf: fix bitrotted kerneldoc

Over the years, the function signature has changed, but the
kerneldoc block hasn't.

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>