Doing this matches the natural type of 'int' based calculus
in sched_rt_handler(), and also enables the adding in of a
correct upper bounds check on the sysctl interface.

[ mingo: Rewrote the changelog. ]
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231008021538.3063250-1-yajun.deng@linux.dev