sched/topology: Fix sched_numa_find_nth_cpu() comment

Reword sched_numa_find_nth_cpu() comment and make it kernel-doc compatible.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-7-yury.norov@gmail.com